Merge pull request #17 from MichaelTheShifter/shiftui_integration

Shiftui integration

1 files changed, 4613 insertions, 0 deletions

diff --git a/source/ShiftUI/Internal/TextControl.cs b/source/ShiftUI/Internal/TextControl.cs
new file mode 100644
index 0000000..65dd5c6
--- /dev/null
+++ b/source/ShiftUI/Internal/TextControl.cs
@@ -0,0 +1,4613 @@
+// Permission is hereby granted, free of charge, to any person obtaining
+// a copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to
+// permit persons to whom the Software is furnished to do so, subject to
+// the following conditions:
+// 
+// The above copyright notice and this permission notice shall be
+// included in all copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+//
+// Copyright (c) 2004-2006 Novell, Inc. (http://www.novell.com)
+//
+// Authors:
+//	Peter Bartok	[email protected]
+//
+//
+
+// NOT COMPLETE
+
+// There's still plenty of things missing, I've got most of it planned, just hadn't had
+// the time to write it all yet.
+// Stuff missing (in no particular order):
+// - Align text after RecalculateLine
+// - Implement tag types for hotlinks, etc.
+// - Implement CaretPgUp/PgDown
+
+// NOTE:
+// selection_start.pos and selection_end.pos are 0-based
+// selection_start.pos = first selected char
+// selection_end.pos = first NOT-selected char
+//
+// FormatText methods are 1-based (as are all tags, LineTag.Start is 1 for 
+// the first character on a line; the reason is that 0 is the position 
+// *before* the first character on a line
+
+
+#undef Debug
+
+using System;
+using System.Collections;
+using System.Drawing;
+using System.Drawing.Text;
+using System.Text;
+using RTF=ShiftUI.RTF;
+
+namespace ShiftUI {
+	internal enum LineColor {
+		Red	= 0,
+		Black	= 1
+	}
+
+	internal enum CaretSelection {
+		Position,	// Selection=Caret
+		Word,		// Selection=Word under caret
+		Line		// Selection=Line under caret
+	}
+
+	[Flags]
+	internal enum FormatSpecified {
+		None,
+
+		BackColor = 2,
+		Font = 4,
+		Color = 8,
+	}
+
+	internal enum CaretDirection {
+		CharForward,	// Move a char to the right
+		CharBack,	// Move a char to the left
+		LineUp,		// Move a line up
+		LineDown,	// Move a line down
+		Home,		// Move to the beginning of the line
+		End,		// Move to the end of the line
+		PgUp,		// Move one page up
+		PgDn,		// Move one page down
+		CtrlPgUp,	// Move caret to the first visible char in the viewport
+		CtrlPgDn,	// Move caret to the last visible char in the viewport
+		CtrlHome,	// Move to the beginning of the document
+		CtrlEnd,	// Move to the end of the document
+		WordBack,	// Move to the beginning of the previous word (or beginning of line)
+		WordForward,	// Move to the beginning of the next word (or end of line)
+		SelectionStart,	// Move to the beginning of the current selection
+		SelectionEnd,	// Move to the end of the current selection
+		CharForwardNoWrap,   // Move a char forward, but don't wrap onto the next line
+		CharBackNoWrap      // Move a char backward, but don't wrap onto the previous line
+	}
+
+	internal enum LineEnding {
+		Wrap = 1,    // line wraps to the next line
+		Limp = 2,    // \r
+		Hard = 4,    // \r\n
+		Soft = 8,    // \r\r\n
+		Rich = 16,    // \n
+
+		None = 0
+	}
+	
+	internal class Document : ICloneable, IEnumerable {
+		#region Structures
+		// FIXME - go through code and check for places where
+		// we do explicit comparisons instead of using the compare overloads
+		internal struct Marker {
+			internal Line		line;
+			internal LineTag	tag;
+			internal int		pos;
+			internal int		height;
+
+			public static bool operator<(Marker lhs, Marker rhs) {
+				if (lhs.line.line_no < rhs.line.line_no) {
+					return true;
+				}
+
+				if (lhs.line.line_no == rhs.line.line_no) {
+					if (lhs.pos < rhs.pos) {
+						return true;
+					}
+				}
+				return false;
+			}
+
+			public static bool operator>(Marker lhs, Marker rhs) {
+				if (lhs.line.line_no > rhs.line.line_no) {
+					return true;
+				}
+
+				if (lhs.line.line_no == rhs.line.line_no) {
+					if (lhs.pos > rhs.pos) {
+						return true;
+					}
+				}
+				return false;
+			}
+
+			public static bool operator==(Marker lhs, Marker rhs) {
+				if ((lhs.line.line_no == rhs.line.line_no) && (lhs.pos == rhs.pos)) {
+					return true;
+				}
+				return false;
+			}
+
+			public static bool operator!=(Marker lhs, Marker rhs) {
+				if ((lhs.line.line_no != rhs.line.line_no) || (lhs.pos != rhs.pos)) {
+					return true;
+				}
+				return false;
+			}
+
+			public void Combine(Line move_to_line, int move_to_line_length) {
+				line = move_to_line;
+				pos += move_to_line_length;
+				tag = LineTag.FindTag(line, pos);
+			}
+
+			// This is for future use, right now Document.Split does it by hand, with some added shortcut logic
+			public void Split(Line move_to_line, int split_at) {
+				line = move_to_line;
+				pos -= split_at;
+				tag = LineTag.FindTag(line, pos);
+			}
+
+			public override bool Equals(object obj) {
+				   return this==(Marker)obj;
+			}
+
+			public override int GetHashCode() {
+				return base.GetHashCode ();
+			}
+
+			public override string ToString() {
+				return "Marker Line " + line + ", Position " + pos;
+			}
+
+		}
+		#endregion Structures
+
+		#region Local Variables
+		private Line		document;
+		private int		lines;
+		private Line		sentinel;
+		private int		document_id;
+		private Random		random = new Random();
+		internal string		password_char;
+		private StringBuilder	password_cache;
+		private bool		calc_pass;
+		private int		char_count;
+		private bool		enable_links;
+
+		// For calculating widths/heights
+		public static readonly StringFormat string_format = new StringFormat (StringFormat.GenericTypographic);
+
+		private int 		recalc_suspended;
+		private bool		recalc_pending;
+		private int		recalc_start = 1;   // This starts at one, since lines are 1 based
+		private int		recalc_end;
+		private bool		recalc_optimize;
+
+		private int             update_suspended;
+		private bool update_pending;
+		private int update_start = 1;
+
+		internal bool		multiline;
+		internal HorizontalAlignment alignment;
+		internal bool		wrap;
+
+		internal UndoManager	undo;
+
+		internal Marker		caret;
+		internal Marker		selection_start;
+		internal Marker		selection_end;
+		internal bool		selection_visible;
+		internal Marker		selection_anchor;
+		internal Marker		selection_prev;
+		internal bool		selection_end_anchor;
+
+		internal int		viewport_x;
+		internal int		viewport_y;		// The visible area of the document
+		internal int		offset_x;
+		internal int		offset_y;
+		internal int		viewport_width;
+		internal int		viewport_height;
+
+		internal int		document_x;		// Width of the document
+		internal int		document_y;		// Height of the document
+
+		internal int		crlf_size;		// 1 or 2, depending on whether we use \r\n or just \n
+
+		internal TextBoxBase	owner;			// Who's owning us?
+		static internal int	caret_width = 1;
+		static internal int	caret_shift = 1;
+
+		internal int left_margin = 2;  // A left margin for all lines
+		internal int top_margin = 2;
+		internal int right_margin = 2;
+		#endregion	// Local Variables
+
+		#region Constructors
+		internal Document (TextBoxBase owner)
+		{
+			lines = 0;
+
+			this.owner = owner;
+
+			multiline = true;
+			password_char = "";
+			calc_pass = false;
+			recalc_pending = false;
+
+			// Tree related stuff
+			sentinel = new Line (this, LineEnding.None);
+			sentinel.color = LineColor.Black;
+
+			document = sentinel;
+
+			// We always have a blank line
+			owner.HandleCreated += new EventHandler(owner_HandleCreated);
+			owner.VisibleChanged += new EventHandler(owner_VisibleChanged);
+
+			Add (1, String.Empty, owner.Font, owner.ForeColor, LineEnding.None);
+
+			undo = new UndoManager (this);
+
+			selection_visible = false;
+			selection_start.line = this.document;
+			selection_start.pos = 0;
+			selection_start.tag = selection_start.line.tags;
+			selection_end.line = this.document;
+			selection_end.pos = 0;
+			selection_end.tag = selection_end.line.tags;
+			selection_anchor.line = this.document;
+			selection_anchor.pos = 0;
+			selection_anchor.tag = selection_anchor.line.tags;
+			caret.line = this.document;
+			caret.pos = 0;
+			caret.tag = caret.line.tags;
+
+			viewport_x = 0;
+			viewport_y = 0;
+
+			offset_x = 0;
+			offset_y = 0;
+
+			crlf_size = 2;
+
+			// Default selection is empty
+
+			document_id = random.Next();
+
+			string_format.Trimming = StringTrimming.None;
+			string_format.FormatFlags = StringFormatFlags.DisplayFormatControl;
+
+			UpdateMargins ();
+		}
+		#endregion
+
+		#region Internal Properties
+		internal Line Root {
+			get {
+				return document;
+			}
+
+			set {
+				document = value;
+			}
+		}
+
+		// UIA: Method used via reflection in TextRangeProvider
+		internal int Lines {
+			get {
+				return lines;
+			}
+		}
+
+		internal Line CaretLine {
+			get {
+				return caret.line;
+			}
+		}
+
+		internal int CaretPosition {
+			get {
+				return caret.pos;
+			}
+		}
+
+		internal Point Caret {
+			get {
+				return new Point((int)caret.tag.Line.widths[caret.pos] + caret.line.X, caret.line.Y);
+			}
+		}
+
+		internal LineTag CaretTag {
+			get {
+				return caret.tag;
+			}
+
+			set {
+				caret.tag = value;
+			}
+		}
+
+		internal int CRLFSize {
+			get {
+				return crlf_size;
+			}
+
+			set {
+				crlf_size = value;
+			}
+		}
+
+		/// <summary>
+		///  Whether text is scanned for links
+		/// </summary>
+		internal bool EnableLinks {
+			get { return enable_links; }
+			set { enable_links = value; }
+		}
+
+		internal string PasswordChar {
+			get {
+				return password_char;
+			}
+
+			set {
+				password_char = value;
+				PasswordCache.Length = 0;
+				if ((password_char.Length != 0) && (password_char[0] != '\0')) {
+					calc_pass = true;
+				} else {
+					calc_pass = false;
+				}
+			}
+		}
+
+		private StringBuilder PasswordCache {
+			get { 
+				if (password_cache == null) 
+					  password_cache = new StringBuilder(); 
+				return password_cache;
+			}
+		}
+
+		internal int ViewPortX {
+			get {
+				return viewport_x;
+			}
+
+			set {
+				viewport_x = value;
+			}
+		}
+
+		internal int Length {
+			get {
+				return char_count + lines - 1;	// Add \n for each line but the last
+			}
+		}
+
+		private int CharCount {
+			get {
+				return char_count;
+			}
+
+			set {
+				char_count = value;
+
+				if (LengthChanged != null) {
+					LengthChanged(this, EventArgs.Empty);
+				}
+			}
+		}
+
+		internal int ViewPortY {
+			get {
+				return viewport_y;
+			}
+
+			set {
+				viewport_y = value;
+			}
+		}
+
+		internal int OffsetX
+		{
+			get
+			{
+				return offset_x;
+			}
+
+			set
+			{
+				offset_x = value;
+			}
+		}
+
+		internal int OffsetY
+		{
+			get
+			{
+				return offset_y;
+			}
+
+			set
+			{
+				offset_y = value;
+			}
+		}
+
+		internal int ViewPortWidth {
+			get {
+				return viewport_width;
+			}
+
+			set {
+				viewport_width = value;
+			}
+		}
+
+		internal int ViewPortHeight {
+			get {
+				return viewport_height;
+			}
+
+			set {
+				viewport_height = value;
+			}
+		}
+
+
+		internal int Width {
+			get {
+				return this.document_x;
+			}
+		}
+
+		internal int Height {
+			get {
+				return this.document_y;
+			}
+		}
+
+		internal bool SelectionVisible {
+			get {
+				return selection_visible;
+			}
+		}
+
+		internal bool Wrap {
+			get {
+				return wrap;
+			}
+
+			set {
+				wrap = value;
+			}
+		}
+
+		#endregion	// Internal Properties
+
+		#region Private Methods
+
+		internal void UpdateMargins ()
+		{
+			switch (owner.actual_border_style) {
+				case BorderStyle.None:
+					left_margin = 0;
+					top_margin = 0;
+					right_margin = 1;
+					break;
+				case BorderStyle.FixedSingle:
+					left_margin = 2;
+					top_margin = 2;
+					right_margin = 3;
+					break;
+				case BorderStyle.Fixed3D:
+					left_margin = 1;
+					top_margin = 1;
+					right_margin = 2;
+					break;
+			}
+		}
+
+		internal void SuspendRecalc ()
+		{
+			if (recalc_suspended == 0) {
+				recalc_start = int.MaxValue;
+				recalc_end = int.MinValue;
+			}
+			
+			recalc_suspended++;
+		}
+
+		internal void ResumeRecalc (bool immediate_update)
+		{
+			if (recalc_suspended > 0)
+				recalc_suspended--;
+
+			if (recalc_suspended == 0 && (immediate_update || recalc_pending) && !(recalc_start == int.MaxValue && recalc_end == int.MinValue)) {
+				RecalculateDocument (owner.CreateGraphicsInternal (), recalc_start, recalc_end, recalc_optimize);
+				recalc_pending = false;
+			}
+		}
+
+		internal void SuspendUpdate ()
+		{
+			update_suspended++;
+		}
+
+		internal void ResumeUpdate (bool immediate_update)
+		{
+			if (update_suspended > 0)
+				update_suspended--;
+
+			if (immediate_update && update_suspended == 0 && update_pending) {
+				UpdateView (GetLine (update_start), 0);
+				update_pending = false;
+			}
+		}
+
+		// For debugging
+		internal int DumpTree(Line line, bool with_tags) {
+			int	total;
+
+			total = 1;
+
+			Console.Write("Line {0} [# {1}], Y: {2}, ending style: {3},  Text: '{4}'",
+					line.line_no, line.GetHashCode(), line.Y, line.ending,
+					line.text != null ? line.text.ToString() : "undefined");
+
+			if (line.left == sentinel) {
+				Console.Write(", left = sentinel");
+			} else if (line.left == null) {
+				Console.Write(", left = NULL");
+			}
+
+			if (line.right == sentinel) {
+				Console.Write(", right = sentinel");
+			} else if (line.right == null) {
+				Console.Write(", right = NULL");
+			}
+
+			Console.WriteLine("");
+
+			if (with_tags) {
+				LineTag	tag;
+				int	count;
+				int	length;
+
+				tag = line.tags;
+				count = 1;
+				length = 0;
+				Console.Write("   Tags: ");
+				while (tag != null) {
+					Console.Write("{0} <{1}>-<{2}>", count++, tag.Start, tag.End
+							/*line.text.ToString (tag.start - 1, tag.length)*/);
+					length += tag.Length;
+
+					if (tag.Line != line) {
+						Console.Write("BAD line link");
+						throw new Exception("Bad line link in tree");
+					}
+					tag = tag.Next;
+					if (tag != null) {
+						Console.Write(", ");
+					}
+				}
+				if (length > line.text.Length) {
+					throw new Exception(String.Format("Length of tags more than length of text on line (expected {0} calculated {1})", line.text.Length, length));
+				} else if (length < line.text.Length) {
+					throw new Exception(String.Format("Length of tags less than length of text on line (expected {0} calculated {1})", line.text.Length, length));
+				}
+				Console.WriteLine("");
+			}
+			if (line.left != null) {
+				if (line.left != sentinel) {
+					total += DumpTree(line.left, with_tags);
+				}
+			} else {
+				if (line != sentinel) {
+					throw new Exception("Left should not be NULL");
+				}
+			}
+
+			if (line.right != null) {
+				if (line.right != sentinel) {
+					total += DumpTree(line.right, with_tags);
+				}
+			} else {
+				if (line != sentinel) {
+					throw new Exception("Right should not be NULL");
+				}
+			}
+
+			for (int i = 1; i <= this.lines; i++) {
+				if (GetLine(i) == null) {
+					throw new Exception(String.Format("Hole in line order, missing {0}", i));
+				}
+			}
+
+			if (line == this.Root) {
+				if (total < this.lines) {
+					throw new Exception(String.Format("Not enough nodes in tree, found {0}, expected {1}", total, this.lines));
+				} else if (total > this.lines) {
+					throw new Exception(String.Format("Too many nodes in tree, found {0}, expected {1}", total, this.lines));
+				}
+			}
+
+			return total;
+		}
+
+		private void SetSelectionVisible (bool value)
+		{
+			bool old_selection_visible = selection_visible;
+			selection_visible = value;
+
+			// cursor and selection are enemies, we can't have both in the same room at the same time
+			if (owner.IsHandleCreated && !owner.show_caret_w_selection)
+				XplatUI.CaretVisible (owner.Handle, !selection_visible);
+			if (UIASelectionChanged != null && (selection_visible || old_selection_visible))
+				UIASelectionChanged (this, EventArgs.Empty);
+		}
+
+		private void DecrementLines(int line_no) {
+			int	current;
+
+			current = line_no;
+			while (current <= lines) {
+				GetLine(current).line_no--;
+				current++;
+			}
+			return;
+		}
+
+		private void IncrementLines(int line_no) {
+			int	current;
+
+			current = this.lines;
+			while (current >= line_no) {
+				GetLine(current).line_no++;
+				current--;
+			}
+			return;
+		}
+
+		private void RebalanceAfterAdd(Line line1) {
+			Line	line2;
+
+			while ((line1 != document) && (line1.parent.color == LineColor.Red)) {
+				if (line1.parent == line1.parent.parent.left) {
+					line2 = line1.parent.parent.right;
+
+					if ((line2 != null) && (line2.color == LineColor.Red)) {
+						line1.parent.color = LineColor.Black;
+						line2.color = LineColor.Black;
+						line1.parent.parent.color = LineColor.Red;
+						line1 = line1.parent.parent;
+					} else {
+						if (line1 == line1.parent.right) {
+							line1 = line1.parent;
+							RotateLeft(line1);
+						}
+
+						line1.parent.color = LineColor.Black;
+						line1.parent.parent.color = LineColor.Red;
+
+						RotateRight(line1.parent.parent);
+					}
+				} else {
+					line2 = line1.parent.parent.left;
+
+					if ((line2 != null) && (line2.color == LineColor.Red)) {
+						line1.parent.color = LineColor.Black;
+						line2.color = LineColor.Black;
+						line1.parent.parent.color = LineColor.Red;
+						line1 = line1.parent.parent;
+					} else {
+						if (line1 == line1.parent.left) {
+							line1 = line1.parent;
+							RotateRight(line1);
+						}
+
+						line1.parent.color = LineColor.Black;
+						line1.parent.parent.color = LineColor.Red;
+						RotateLeft(line1.parent.parent);
+					}
+				}
+			}
+			document.color = LineColor.Black;
+		}
+
+		private void RebalanceAfterDelete(Line line1) {
+			Line line2;
+
+			while ((line1 != document) && (line1.color == LineColor.Black)) {
+				if (line1 == line1.parent.left) {
+					line2 = line1.parent.right;
+					if (line2.color == LineColor.Red) { 
+						line2.color = LineColor.Black;
+						line1.parent.color = LineColor.Red;
+						RotateLeft(line1.parent);
+						line2 = line1.parent.right;
+					}
+					if ((line2.left.color == LineColor.Black) && (line2.right.color == LineColor.Black)) { 
+						line2.color = LineColor.Red;
+						line1 = line1.parent;
+					} else {
+						if (line2.right.color == LineColor.Black) {
+							line2.left.color = LineColor.Black;
+							line2.color = LineColor.Red;
+							RotateRight(line2);
+							line2 = line1.parent.right;
+						}
+						line2.color = line1.parent.color;
+						line1.parent.color = LineColor.Black;
+						line2.right.color = LineColor.Black;
+						RotateLeft(line1.parent);
+						line1 = document;
+					}
+				} else { 
+					line2 = line1.parent.left;
+					if (line2.color == LineColor.Red) {
+						line2.color = LineColor.Black;
+						line1.parent.color = LineColor.Red;
+						RotateRight(line1.parent);
+						line2 = line1.parent.left;
+					}
+					if ((line2.right.color == LineColor.Black) && (line2.left.color == LineColor.Black)) {
+						line2.color = LineColor.Red;
+						line1 = line1.parent;
+					} else {
+						if (line2.left.color == LineColor.Black) {
+							line2.right.color = LineColor.Black;
+							line2.color = LineColor.Red;
+							RotateLeft(line2);
+							line2 = line1.parent.left;
+						}
+						line2.color = line1.parent.color;
+						line1.parent.color = LineColor.Black;
+						line2.left.color = LineColor.Black;
+						RotateRight(line1.parent);
+						line1 = document;
+					}
+				}
+			}
+			line1.color = LineColor.Black;
+		}
+
+		private void RotateLeft(Line line1) {
+			Line	line2 = line1.right;
+
+			line1.right = line2.left;
+
+			if (line2.left != sentinel) {
+				line2.left.parent = line1;
+			}
+
+			if (line2 != sentinel) {
+				line2.parent = line1.parent;
+			}
+
+			if (line1.parent != null) {
+				if (line1 == line1.parent.left) {
+					line1.parent.left = line2;
+				} else {
+					line1.parent.right = line2;
+				}
+			} else {
+				document = line2;
+			}
+
+			line2.left = line1;
+			if (line1 != sentinel) {
+				line1.parent = line2;
+			}
+		}
+
+		private void RotateRight(Line line1) {
+			Line line2 = line1.left;
+
+			line1.left = line2.right;
+
+			if (line2.right != sentinel) {
+				line2.right.parent = line1;
+			}
+
+			if (line2 != sentinel) {
+				line2.parent = line1.parent;
+			}
+
+			if (line1.parent != null) {
+				if (line1 == line1.parent.right) {
+					line1.parent.right = line2;
+				} else {
+					line1.parent.left = line2;
+				}
+			} else {
+				document = line2;
+			}
+
+			line2.right = line1;
+			if (line1 != sentinel) {
+				line1.parent = line2;
+			}
+		}        
+
+
+		internal void UpdateView(Line line, int pos) {
+			if (!owner.IsHandleCreated) {
+				return;
+			}
+
+			if (update_suspended > 0) {
+				update_start = Math.Min (update_start, line.line_no);
+				// update_end = Math.Max (update_end, line.line_no);
+				// recalc_optimize = true;
+				update_pending = true;
+				return;
+			}
+
+			// Optimize invalidation based on Line alignment
+			if (RecalculateDocument(owner.CreateGraphicsInternal(), line.line_no, line.line_no, true)) {
+				// Lineheight changed, invalidate the rest of the document
+				if ((line.Y - viewport_y) >=0 ) {
+					// We formatted something that's in view, only draw parts of the screen
+					owner.Invalidate(new Rectangle(
+						offset_x, 
+						line.Y - viewport_y + offset_y, 
+						viewport_width, 
+						owner.Height - (line.Y - viewport_y)));
+				} else {
+					// The tag was above the visible area, draw everything
+					owner.Invalidate();
+				}
+			} else {
+				switch(line.alignment) {
+					case HorizontalAlignment.Left: {
+						owner.Invalidate(new Rectangle(
+							line.X + ((int)line.widths[pos] - viewport_x - 1) + offset_x, 
+							line.Y - viewport_y + offset_y, 
+							viewport_width, 
+							line.height + 1));
+						break;
+					}
+
+					case HorizontalAlignment.Center: {
+						owner.Invalidate(new Rectangle(
+							line.X + offset_x, 
+							line.Y - viewport_y + offset_y, 
+							viewport_width, 
+							line.height + 1));
+						break;
+					}
+
+					case HorizontalAlignment.Right: {
+						owner.Invalidate(new Rectangle(
+							line.X + offset_x, 
+							line.Y - viewport_y + offset_y, 
+							(int)line.widths[pos + 1] - viewport_x + line.X, 
+							line.height + 1));
+						break;
+					}
+				}
+			}
+		}
+
+
+		// Update display from line, down line_count lines; pos is unused, but required for the signature
+		internal void UpdateView(Line line, int line_count, int pos) {
+			if (!owner.IsHandleCreated) {
+				return;
+			}
+
+			if (recalc_suspended > 0) {
+				recalc_start = Math.Min (recalc_start, line.line_no);
+				recalc_end = Math.Max (recalc_end, line.line_no + line_count);
+				recalc_optimize = true;
+				recalc_pending = true;
+				return;
+			}
+
+			int start_line_top = line.Y;			
+
+			Line end_line = GetLine (line.line_no + line_count);
+			if (end_line == null)
+				end_line = GetLine (lines);
+
+			if (end_line == null)
+				return;
+			
+			int end_line_bottom = end_line.Y + end_line.height;
+			
+			if (RecalculateDocument(owner.CreateGraphicsInternal(), line.line_no, line.line_no + line_count, true)) {
+				// Lineheight changed, invalidate the rest of the document
+				if ((line.Y - viewport_y) >=0 ) {
+					// We formatted something that's in view, only draw parts of the screen
+					owner.Invalidate(new Rectangle(
+						offset_x, 
+						line.Y - viewport_y + offset_y, 
+						viewport_width, 
+						owner.Height - (line.Y - viewport_y)));
+				} else {
+					// The tag was above the visible area, draw everything
+					owner.Invalidate();
+				}
+			} else {
+				int x = 0 - viewport_x + offset_x;
+				int w = viewport_width;
+				int y = Math.Min (start_line_top - viewport_y, line.Y - viewport_y) + offset_y;
+				int h = Math.Max (end_line_bottom - y, end_line.Y + end_line.height - y);
+
+				owner.Invalidate (new Rectangle (x, y, w, h));
+			}
+		}
+
+		/// <summary>
+		///  Scans the next paragraph for http:/ ftp:/ www. https:/ etc and marks the tags
+		///  as links.
+		/// </summary>
+		/// <param name="start_line">The line to start on</param>
+		/// <param name="link_changed">marks as true if something is changed</param>
+		private void ScanForLinks (Line start_line, ref bool link_changed)
+		{
+			Line current_line = start_line;
+			StringBuilder line_no_breaks = new StringBuilder ();
+			StringBuilder line_link_record = new StringBuilder ();
+			ArrayList cumulative_length_list = new ArrayList ();
+			bool update_caret_tag = false;
+
+			cumulative_length_list.Add (0);
+
+			while (current_line != null) {
+				line_no_breaks.Append (current_line.text);
+
+				if (link_changed == false)
+					current_line.LinkRecord (line_link_record);
+
+				current_line.ClearLinks ();
+
+				cumulative_length_list.Add (line_no_breaks.Length);
+
+				if (current_line.ending == LineEnding.Wrap)
+					current_line = GetLine (current_line.LineNo + 1);
+				else
+					break;
+			}
+
+			// search for protocols.. make sure www. is first!
+			string [] search_terms = new string [] { "www.", "http:/", "ftp:/", "https:/" };
+			int search_found = 0;
+			int index_found = 0;
+			string line_no_breaks_string = line_no_breaks.ToString ();
+			int line_no_breaks_index = 0;
+			int link_end = 0;
+
+			while (true) {
+				if (line_no_breaks_index >= line_no_breaks_string.Length)
+					break;
+
+				index_found = FirstIndexOfAny (line_no_breaks_string, search_terms, line_no_breaks_index, out search_found);
+
+				//no links found on this line
+				if (index_found == -1)
+					break;
+
+				if (search_found == 0) {
+					// if we are at the end of the line to analyse and the end of the line
+					// is "www." then there are no links here
+					if (line_no_breaks_string.Length == index_found + search_terms [0].Length)
+						break;
+
+					// if after www. we don't have a letter a digit or a @ or - or /
+					// then it is not a web address, we should continue searching
+					if (char.IsLetterOrDigit (line_no_breaks_string [index_found + search_terms [0].Length]) == false &&
+						"@/~".IndexOf (line_no_breaks_string [index_found + search_terms [0].Length].ToString ()) == -1) {
+						line_no_breaks_index = index_found + search_terms [0].Length;
+						continue;
+					}
+				}
+
+				link_end = line_no_breaks_string.Length - 1;
+				line_no_breaks_index = line_no_breaks_string.Length;
+
+				// we've found a link, we just need to find where it ends now
+				for (int i = index_found + search_terms [search_found].Length; i < line_no_breaks_string.Length; i++) {
+					if (line_no_breaks_string [i - 1] == '.') {
+						if (char.IsLetterOrDigit (line_no_breaks_string [i]) == false &&
+							"@/~".IndexOf (line_no_breaks_string [i].ToString ()) == -1) {
+							link_end = i - 1;
+							line_no_breaks_index = i;
+							break;
+						}
+					} else {
+						if (char.IsLetterOrDigit (line_no_breaks_string [i]) == false &&
+							"@-/:~.?=_&".IndexOf (line_no_breaks_string [i].ToString ()) == -1) {
+							link_end = i - 1;
+							line_no_breaks_index = i;
+							break;
+						}
+					}
+				}
+
+				string link_text = line_no_breaks_string.Substring (index_found, link_end - index_found + 1);
+				int current_cumulative = 0;
+
+				// we've found a link - index_found -> link_end
+				// now we just make all the tags as containing link and
+				// point them to the text for the whole link
+
+				current_line = start_line;
+
+				//find the line we start on
+				for (current_cumulative = 1; current_cumulative < cumulative_length_list.Count; current_cumulative++)
+					if ((int)cumulative_length_list [current_cumulative] > index_found)
+						break;
+
+				current_line = GetLine (start_line.LineNo + current_cumulative - 1);
+
+				// find the tag we start on
+				LineTag current_tag = current_line.FindTag (index_found - (int)cumulative_length_list [current_cumulative - 1] + 1);
+
+				if (current_tag.Start != (index_found - (int)cumulative_length_list [current_cumulative - 1]) + 1) {
+					if (current_tag == CaretTag)
+						update_caret_tag = true;
+
+					current_tag = current_tag.Break ((index_found - (int)cumulative_length_list [current_cumulative - 1]) + 1);
+				}
+
+				// set the tag
+				current_tag.IsLink = true;
+				current_tag.LinkText = link_text;
+
+				//go through each character
+				// find the tag we are in
+				// skip the number of characters in the tag
+				for (int i = 1; i < link_text.Length; i++) {
+					// on to a new word-wrapped line
+					if ((int)cumulative_length_list [current_cumulative] <= index_found + i) {
+
+						current_line = GetLine (start_line.LineNo + current_cumulative++);
+						current_tag = current_line.FindTag (index_found + i - (int)cumulative_length_list [current_cumulative - 1] + 1);
+
+						current_tag.IsLink = true;
+						current_tag.LinkText = link_text;
+
+						continue;
+					}
+
+					if (current_tag.End < index_found + 1 + i - (int)cumulative_length_list [current_cumulative - 1]) {
+						// skip empty tags in the middle of the URL
+						do {
+							current_tag = current_tag.Next;
+						} while (current_tag.Length == 0);
+
+						current_tag.IsLink = true;
+						current_tag.LinkText = link_text;
+					}
+				}
+
+				//if there are characters left in the tag after the link
+				// split the tag
+				// make the second part a non link
+				if (current_tag.End > (index_found + link_text.Length + 1) - (int)cumulative_length_list [current_cumulative - 1]) {
+					if (current_tag == CaretTag)
+						update_caret_tag = true;
+
+					current_tag.Break ((index_found + link_text.Length + 1) - (int)cumulative_length_list [current_cumulative - 1]);
+				}
+			}
+
+			if (update_caret_tag) {
+				CaretTag = LineTag.FindTag (CaretLine, CaretPosition);
+				link_changed = true;
+			} else {
+				if (link_changed == false) {
+					current_line = start_line;
+					StringBuilder new_link_record = new StringBuilder ();
+
+					while (current_line != null) {
+						current_line.LinkRecord (new_link_record);
+
+						if (current_line.ending == LineEnding.Wrap)
+							current_line = GetLine (current_line.LineNo + 1);
+						else
+							break;
+					}
+
+					if (new_link_record.Equals (line_link_record) == false)
+						link_changed = true;
+				}
+			}
+		}
+
+		private int FirstIndexOfAny (string haystack, string [] needles, int start_index, out int term_found)
+		{
+			term_found = -1;
+			int best_index = -1;
+
+			for (int i = 0; i < needles.Length; i++) {
+				int index = haystack.IndexOf (needles [i], start_index,	StringComparison.InvariantCultureIgnoreCase);
+
+				if (index > -1) {
+					if (term_found > -1) {
+						if (index < best_index) {
+							best_index = index;
+							term_found = i;
+						}
+					} else {
+						best_index = index;
+						term_found = i;
+					}
+				}
+			}
+
+			return best_index;
+		}
+
+
+
+		private void InvalidateLinks (Rectangle clip)
+		{
+			for (int i = (owner.list_links.Count - 1); i >= 0; i--) {
+				TextBoxBase.LinkRectangle link = (TextBoxBase.LinkRectangle) owner.list_links [i];
+
+				if (clip.IntersectsWith (link.LinkAreaRectangle))
+					owner.list_links.RemoveAt (i);
+			}
+		}
+		#endregion	// Private Methods
+
+		#region Internal Methods
+
+		internal void ScanForLinks (int start, int end, ref bool link_changed)
+		{
+			Line line = null;
+			LineEnding lastending = LineEnding.Rich;
+
+			// make sure we start scanning at the real begining of the line
+			while (true) {
+				if (start != 1 && GetLine (start - 1).ending == LineEnding.Wrap)
+					start--;
+				else
+					break;
+			}
+
+			for (int i = start; i <= end && i <= lines; i++) {
+				line = GetLine (i);
+
+				if (lastending != LineEnding.Wrap)
+					ScanForLinks (line, ref link_changed);
+
+				lastending = line.ending;
+
+				if (lastending == LineEnding.Wrap && (i + 1) <= end)
+					end++;
+			}
+		}
+
+		// Clear the document and reset state
+		internal void Empty() {
+
+			document = sentinel;
+			lines = 0;
+
+			// We always have a blank line
+			Add (1, String.Empty, owner.Font, owner.ForeColor, LineEnding.None);
+			
+			this.RecalculateDocument(owner.CreateGraphicsInternal());
+			PositionCaret(0, 0);
+
+			SetSelectionVisible (false);
+
+			selection_start.line = this.document;
+			selection_start.pos = 0;
+			selection_start.tag = selection_start.line.tags;
+			selection_end.line = this.document;
+			selection_end.pos = 0;
+			selection_end.tag = selection_end.line.tags;
+			char_count = 0;
+
+			viewport_x = 0;
+			viewport_y = 0;
+
+			document_x = 0;
+			document_y = 0;
+
+			if (owner.IsHandleCreated)
+				owner.Invalidate ();
+		}
+
+		internal void PositionCaret(Line line, int pos) {
+			caret.tag = line.FindTag (pos);
+
+			MoveCaretToTextTag ();
+
+			caret.line = line;
+			caret.pos = pos;
+
+			if (owner.IsHandleCreated) {
+				if (owner.Focused) {
+					if (caret.height != caret.tag.Height)
+						XplatUI.CreateCaret (owner.Handle, caret_width, caret.height);
+					XplatUI.SetCaretPos(owner.Handle, 
+						offset_x + (int)caret.tag.Line.widths[caret.pos] + caret.line.X - viewport_x, 
+						offset_y + caret.line.Y + caret.tag.Shift - viewport_y + caret_shift);
+				}
+
+				if (CaretMoved != null) CaretMoved(this, EventArgs.Empty);
+			}
+
+			// We set this at the end because we use the heights to determine whether or
+			// not we need to recreate the caret
+			caret.height = caret.tag.Height;
+
+		}
+
+		internal void PositionCaret(int x, int y) {
+			if (!owner.IsHandleCreated) {
+				return;
+			}
+
+			caret.tag = FindCursor(x, y, out caret.pos);
+			
+			MoveCaretToTextTag ();
+			
+			caret.line = caret.tag.Line;
+			caret.height = caret.tag.Height;
+
+			if (owner.ShowSelection && (!selection_visible || owner.show_caret_w_selection)) {
+				XplatUI.CreateCaret (owner.Handle, caret_width, caret.height);
+				XplatUI.SetCaretPos(owner.Handle, 
+					(int)caret.tag.Line.widths[caret.pos] + caret.line.X - viewport_x + offset_x, 
+					offset_y + caret.line.Y + caret.tag.Shift - viewport_y + caret_shift);
+			}
+
+			if (CaretMoved != null) CaretMoved(this, EventArgs.Empty);
+		}
+
+		internal void CaretHasFocus() {
+			if ((caret.tag != null) && owner.IsHandleCreated) {
+				XplatUI.CreateCaret(owner.Handle, caret_width, caret.height);
+				XplatUI.SetCaretPos(owner.Handle, 
+					offset_x + (int)caret.tag.Line.widths[caret.pos] + caret.line.X - viewport_x, 
+					offset_y + caret.line.Y + caret.tag.Shift - viewport_y + caret_shift);
+
+				DisplayCaret ();
+			}
+
+			if (owner.IsHandleCreated && SelectionLength () > 0) {
+				InvalidateSelectionArea ();
+			}
+		}
+
+		internal void CaretLostFocus() {
+			if (!owner.IsHandleCreated) {
+				return;
+			}
+			XplatUI.DestroyCaret(owner.Handle);
+		}
+
+		internal void AlignCaret ()
+		{
+			AlignCaret (true);
+		}
+
+		internal void AlignCaret(bool changeCaretTag) {
+			if (!owner.IsHandleCreated) {
+				return;
+			}
+
+			if (changeCaretTag) {
+				caret.tag = LineTag.FindTag (caret.line, caret.pos);
+
+				MoveCaretToTextTag ();
+			}
+
+			// if the caret has had SelectionFont changed to a
+			// different height, we reflect changes unless the new
+			// font is larger than the line (line recalculations
+			// ignore empty tags) in which case we make it equal
+			// the line height and then when text is entered
+			if (caret.tag.Height > caret.tag.Line.Height) {
+				caret.height = caret.line.height;
+			} else {
+				caret.height = caret.tag.Height;
+			}
+
+			if (owner.Focused) {
+				XplatUI.CreateCaret(owner.Handle, caret_width, caret.height);
+				XplatUI.SetCaretPos (owner.Handle, 
+					offset_x + (int) caret.tag.Line.widths [caret.pos] + caret.line.X - viewport_x, 
+					offset_y + caret.line.Y + viewport_y + caret_shift);
+				DisplayCaret ();
+			}
+
+			if (CaretMoved != null) CaretMoved(this, EventArgs.Empty);
+		}
+
+		internal void UpdateCaret() {
+			if (!owner.IsHandleCreated || caret.tag == null) {
+				return;
+			}
+
+			MoveCaretToTextTag ();
+
+			if (caret.tag.Height != caret.height) {
+				caret.height = caret.tag.Height;
+				if (owner.Focused) {
+					XplatUI.CreateCaret(owner.Handle, caret_width, caret.height);
+				}
+			}
+
+			if (owner.Focused) {
+				XplatUI.SetCaretPos(owner.Handle, 
+					offset_x + (int)caret.tag.Line.widths[caret.pos] + caret.line.X - viewport_x, 
+					offset_y + caret.line.Y + caret.tag.Shift - viewport_y + caret_shift);
+				DisplayCaret ();
+			}
+			
+			if (CaretMoved != null) CaretMoved(this, EventArgs.Empty);
+		}
+
+		internal void DisplayCaret() {
+			if (!owner.IsHandleCreated) {
+				return;
+			}
+
+			if (owner.ShowSelection && (!selection_visible || owner.show_caret_w_selection)) {
+				XplatUI.CaretVisible(owner.Handle, true);
+			}
+		}
+
+		internal void HideCaret() {
+			if (!owner.IsHandleCreated) {
+				return;
+			}
+
+			if (owner.Focused) {
+				XplatUI.CaretVisible(owner.Handle, false);
+			}
+		}
+
+		
+		internal void MoveCaretToTextTag ()
+		{
+			if (caret.tag == null || caret.tag.IsTextTag)
+				return;
+
+			
+
+			if (caret.pos < caret.tag.Start) {
+				caret.tag = caret.tag.Previous;
+			} else {
+				caret.tag = caret.tag.Next;
+			}
+		}
+
+		internal void MoveCaret(CaretDirection direction) {
+			// FIXME should we use IsWordSeparator to detect whitespace, instead 
+			// of looking for actual spaces in the Word move cases?
+
+			bool nowrap = false;
+			switch(direction) {
+				case CaretDirection.CharForwardNoWrap:
+					nowrap = true;
+					goto case CaretDirection.CharForward;
+				case CaretDirection.CharForward: {
+					caret.pos++;
+					if (caret.pos > caret.line.TextLengthWithoutEnding ()) {
+						if (!nowrap) {
+							// Go into next line
+							if (caret.line.line_no < this.lines) {
+								caret.line = GetLine(caret.line.line_no+1);
+								caret.pos = 0;
+								caret.tag = caret.line.tags;
+							} else {
+								caret.pos--;
+							}
+						} else {
+							// Single line; we stay where we are
+							caret.pos--;
+						}
+					} else {
+						if ((caret.tag.Start - 1 + caret.tag.Length) < caret.pos) {
+							caret.tag = caret.tag.Next;
+						}
+					}
+					UpdateCaret();
+					return;
+				}
+
+				case CaretDirection.CharBackNoWrap:
+					nowrap = true;
+					goto case CaretDirection.CharBack;
+				case CaretDirection.CharBack: {
+					if (caret.pos > 0) {
+						// caret.pos--; // folded into the if below
+						
+						if (--caret.pos > 0) {
+							if (caret.tag.Start > caret.pos) {
+								caret.tag = caret.tag.Previous;
+							}
+						}
+					} else {
+						if (caret.line.line_no > 1 && !nowrap) {
+							caret.line = GetLine(caret.line.line_no - 1);
+							caret.pos = caret.line.TextLengthWithoutEnding ();
+							caret.tag = LineTag.FindTag(caret.line, caret.pos);
+						}
+					}
+					UpdateCaret();
+					return;
+				}
+
+				case CaretDirection.WordForward: {
+					int len;
+
+					len = caret.line.text.Length;
+					if (caret.pos < len) {
+						while ((caret.pos < len) && (caret.line.text[caret.pos] != ' ')) {
+							caret.pos++;
+						}
+						if (caret.pos < len) {
+							// Skip any whitespace
+							while ((caret.pos < len) && (caret.line.text[caret.pos] == ' ')) {
+								caret.pos++;
+							}
+						}
+						caret.tag = LineTag.FindTag(caret.line, caret.pos);
+					} else {
+						if (caret.line.line_no < this.lines) {
+							caret.line = GetLine(caret.line.line_no + 1);
+							caret.pos = 0;
+							caret.tag = caret.line.tags;
+						}
+					}
+					UpdateCaret();
+					return;
+				}
+
+				case CaretDirection.WordBack: {
+					if (caret.pos > 0) {
+						caret.pos--;
+
+						while ((caret.pos > 0) && (caret.line.text[caret.pos] == ' ')) {
+							caret.pos--;
+						}
+
+						while ((caret.pos > 0) && (caret.line.text[caret.pos] != ' ')) {
+							caret.pos--;
+						}
+
+						if (caret.line.text.ToString(caret.pos, 1) == " ") {
+							if (caret.pos != 0) {
+								caret.pos++;
+							} else {
+								caret.line = GetLine(caret.line.line_no - 1);
+								caret.pos = caret.line.text.Length;
+							}
+						}
+						caret.tag = LineTag.FindTag(caret.line, caret.pos);
+					} else {
+						if (caret.line.line_no > 1) {
+							caret.line = GetLine(caret.line.line_no - 1);
+							caret.pos = caret.line.text.Length;
+							caret.tag = LineTag.FindTag(caret.line, caret.pos);
+						}
+					}
+					UpdateCaret();
+					return;
+				}
+
+				case CaretDirection.LineUp: {
+					if (caret.line.line_no > 1) {
+						int	pixel;
+
+						pixel = (int)caret.line.widths[caret.pos];
+						PositionCaret(pixel, GetLine(caret.line.line_no - 1).Y);
+
+						DisplayCaret ();
+					}
+					return;
+				}
+
+				case CaretDirection.LineDown: {
+					if (caret.line.line_no < lines) {
+						int	pixel;
+
+						pixel = (int)caret.line.widths[caret.pos];
+						PositionCaret(pixel, GetLine(caret.line.line_no + 1).Y);
+
+						DisplayCaret ();
+					}
+					return;
+				}
+
+				case CaretDirection.Home: {
+					if (caret.pos > 0) {
+						caret.pos = 0;
+						caret.tag = caret.line.tags;
+						UpdateCaret();
+					}
+					return;
+				}
+
+				case CaretDirection.End: {
+					if (caret.pos < caret.line.TextLengthWithoutEnding ()) {
+						caret.pos = caret.line.TextLengthWithoutEnding ();
+						caret.tag = LineTag.FindTag(caret.line, caret.pos);
+						UpdateCaret();
+					}
+					return;
+				}
+
+				case CaretDirection.PgUp: {
+
+					if (caret.line.line_no == 1 && owner.richtext) {
+						owner.vscroll.Value = 0;
+						Line line = GetLine (1);
+						PositionCaret (line, 0);
+					}
+
+					int y_offset = caret.line.Y + caret.line.height - 1 - viewport_y;
+					int index;
+					LineTag top = FindCursor ((int) caret.line.widths [caret.pos],
+							viewport_y - viewport_height, out index);
+
+					owner.vscroll.Value = Math.Min (top.Line.Y, owner.vscroll.Maximum - viewport_height);
+					PositionCaret ((int) caret.line.widths [caret.pos], y_offset + viewport_y);
+
+					return;
+				}
+
+				case CaretDirection.PgDn: {
+
+					if (caret.line.line_no == lines && owner.richtext) {
+						owner.vscroll.Value = owner.vscroll.Maximum - viewport_height + 1;
+						Line line = GetLine (lines);
+						PositionCaret (line, line.TextLengthWithoutEnding());
+					}
+
+					int y_offset = caret.line.Y - viewport_y;
+					int index;
+					LineTag top = FindCursor ((int) caret.line.widths [caret.pos],
+							viewport_y + viewport_height, out index);
+
+					owner.vscroll.Value = Math.Min (top.Line.Y, owner.vscroll.Maximum - viewport_height);
+					PositionCaret ((int) caret.line.widths [caret.pos], y_offset + viewport_y);
+					
+					return;
+				}
+
+				case CaretDirection.CtrlPgUp: {
+					PositionCaret(0, viewport_y);
+					DisplayCaret ();
+					return;
+				}
+
+				case CaretDirection.CtrlPgDn: {
+					Line	line;
+					LineTag	tag;
+					int	index;
+
+					tag = FindCursor (0, viewport_y + viewport_height, out index);
+					if (tag.Line.line_no > 1) {
+						line = GetLine(tag.Line.line_no - 1);
+					} else {
+						line = tag.Line;
+					}
+					PositionCaret(line, line.Text.Length);
+					DisplayCaret ();
+					return;
+				}
+
+				case CaretDirection.CtrlHome: {
+					caret.line = GetLine(1);
+					caret.pos = 0;
+					caret.tag = caret.line.tags;
+
+					UpdateCaret();
+					return;
+				}
+
+				case CaretDirection.CtrlEnd: {
+					caret.line = GetLine(lines);
+					caret.pos = caret.line.TextLengthWithoutEnding ();
+					caret.tag = LineTag.FindTag(caret.line, caret.pos);
+
+					UpdateCaret();
+					return;
+				}
+
+				case CaretDirection.SelectionStart: {
+					caret.line = selection_start.line;
+					caret.pos = selection_start.pos;
+					caret.tag = selection_start.tag;
+
+					UpdateCaret();
+					return;
+				}
+
+				case CaretDirection.SelectionEnd: {
+					caret.line = selection_end.line;
+					caret.pos = selection_end.pos;
+					caret.tag = selection_end.tag;
+
+					UpdateCaret();
+					return;
+				}
+			}
+		}
+
+		internal void DumpDoc ()
+		{
+			Console.WriteLine ("<doc lines='{0}'>", lines);
+			for (int i = 1; i <= lines ; i++) {
+				Line line = GetLine (i);
+				Console.WriteLine ("<line no='{0}' ending='{1}'>", line.line_no, line.ending);
+
+				LineTag tag = line.tags;
+				while (tag != null) {
+					Console.Write ("\t<tag type='{0}' span='{1}->{2}' font='{3}' color='{4}'>",
+							tag.GetType (), tag.Start, tag.Length, tag.Font, tag.Color);
+					Console.Write (tag.Text ());
+					Console.WriteLine ("</tag>");
+					tag = tag.Next;
+				}
+				Console.WriteLine ("</line>");
+			}
+			Console.WriteLine ("</doc>");
+		}
+
+		// UIA: Used via reflection by TextProviderBehavior
+		internal void GetVisibleLineIndexes (Rectangle clip, out int start, out int end)
+		{
+			if (multiline) {
+				/* Expand the region slightly to be sure to
+				 * paint the full extent of the line of text.
+				 * See bug 464464.
+				 */
+				start = GetLineByPixel(clip.Top + viewport_y - offset_y - 1, false).line_no;
+				end = GetLineByPixel(clip.Bottom + viewport_y - offset_y + 1, false).line_no;
+			} else {
+				start = GetLineByPixel(clip.Left + viewport_x - offset_x, false).line_no;
+				end = GetLineByPixel(clip.Right + viewport_x - offset_x, false).line_no;
+			}
+		}
+
+		internal void Draw (Graphics g, Rectangle clip)
+		{
+			Line line;		// Current line being drawn
+			LineTag	tag;		// Current tag being drawn
+			int start;		// First line to draw
+			int end;		// Last line to draw
+			StringBuilder text;	// String representing the current line
+			int line_no;
+			Color tag_color;
+			Color current_color;
+
+			// First, figure out from what line to what line we need to draw
+			GetVisibleLineIndexes (clip, out start, out end);
+
+			// remove links in the list (used for mouse down events) that are within the clip area.
+			InvalidateLinks (clip);
+
+			///
+			/// We draw the single border ourself
+			///
+			if (owner.actual_border_style == BorderStyle.FixedSingle) {
+				WidgetPaint.DrawBorder (g, owner.ClientRectangle, Color.Black, ButtonBorderStyle.Solid);
+			}
+
+			/// Make sure that we aren't drawing one more line then we need to
+			line = GetLine (end - 1);
+			if (line != null && clip.Bottom == offset_y + line.Y + line.height - viewport_y)
+				end--;
+
+			line_no = start;
+
+			#if Debug
+				DateTime	n = DateTime.Now;
+				Console.WriteLine ("Started drawing: {0}s {1}ms", n.Second, n.Millisecond);
+				Console.WriteLine ("CLIP:  {0}", clip);
+				Console.WriteLine ("S: {0}", GetLine (start).text);
+				Console.WriteLine ("E: {0}", GetLine (end).text);
+			#endif
+
+			// Non multiline selection can be handled outside of the loop
+			if (!multiline && selection_visible && owner.ShowSelection) {
+				g.FillRectangle (ThemeEngine.Current.ResPool.GetSolidBrush (ThemeEngine.Current.ColorHighlight),
+						offset_x + selection_start.line.widths [selection_start.pos] +
+						selection_start.line.X - viewport_x, 
+						offset_y + selection_start.line.Y,
+						(selection_end.line.X + selection_end.line.widths [selection_end.pos]) -
+						(selection_start.line.X + selection_start.line.widths [selection_start.pos]), 
+						selection_start.line.height);
+			}
+
+			while (line_no <= end) {
+				line = GetLine (line_no);
+				float line_y = line.Y - viewport_y + offset_y;
+				
+				tag = line.tags;
+				if (!calc_pass) {
+					text = line.text;
+				} else {
+					if (PasswordCache.Length < line.text.Length)
+						PasswordCache.Append(Char.Parse(password_char), line.text.Length - PasswordCache.Length);
+					else if (PasswordCache.Length > line.text.Length)
+						PasswordCache.Remove(line.text.Length, PasswordCache.Length - line.text.Length);
+					text = PasswordCache;
+				}
+
+				int line_selection_start = text.Length + 1;
+				int line_selection_end = text.Length + 1;
+				if (selection_visible && owner.ShowSelection &&
+						(line_no >= selection_start.line.line_no) &&
+						(line_no <= selection_end.line.line_no)) {
+
+					if (line_no == selection_start.line.line_no)
+						line_selection_start = selection_start.pos + 1;
+					else
+						line_selection_start = 1;
+
+					if (line_no == selection_end.line.line_no)
+						line_selection_end = selection_end.pos + 1;
+					else
+						line_selection_end = text.Length + 1;
+
+					if (line_selection_end == line_selection_start) {
+						// There isn't really selection
+						line_selection_start = text.Length + 1;
+						line_selection_end = line_selection_start;
+					} else if (multiline) {
+						// lets draw some selection baby!!  (non multiline selection is drawn outside the loop)
+						g.FillRectangle (ThemeEngine.Current.ResPool.GetSolidBrush (ThemeEngine.Current.ColorHighlight),
+								offset_x + line.widths [line_selection_start - 1] + line.X - viewport_x, 
+								line_y, line.widths [line_selection_end - 1] - line.widths [line_selection_start - 1], 
+								line.height);
+					}
+				}
+
+				current_color = line.tags.ColorToDisplay;
+				while (tag != null) {
+
+					// Skip empty tags
+					if (tag.Length == 0) {
+						tag = tag.Next;
+						continue;
+					}
+
+					if (((tag.X + tag.Width) < (clip.Left - viewport_x - offset_x)) && 
+					     (tag.X > (clip.Right - viewport_x - offset_x))) {
+						tag = tag.Next;
+						continue;
+					}
+
+					if (tag.BackColor != Color.Empty) {
+						g.FillRectangle (ThemeEngine.Current.ResPool.GetSolidBrush (tag.BackColor), 
+								offset_x + tag.X + line.X - viewport_x,
+								line_y + tag.Shift, tag.Width, line.height);
+					}
+
+					tag_color = tag.ColorToDisplay;
+					current_color = tag_color;
+
+					if (!owner.Enabled) {
+						Color a = tag.Color;
+						Color b = ThemeEngine.Current.ColorWindowText;
+
+						if ((a.R == b.R) && (a.G == b.G) && (a.B == b.B))
+							tag_color = ThemeEngine.Current.ColorGrayText;
+
+					} 
+
+					int tag_pos = tag.Start;
+					current_color = tag_color;
+					while (tag_pos < tag.Start + tag.Length) {
+						int old_tag_pos = tag_pos;
+
+						if (tag_pos >= line_selection_start && tag_pos < line_selection_end) {
+							current_color = ThemeEngine.Current.ColorHighlightText;
+							tag_pos = Math.Min (tag.End, line_selection_end);
+						} else if (tag_pos < line_selection_start) {
+							current_color = tag_color;
+							tag_pos = Math.Min (tag.End, line_selection_start);
+						} else {
+							current_color = tag_color;
+							tag_pos = tag.End;
+						}
+
+						Rectangle text_size;
+
+						tag.Draw (g, current_color,
+								offset_x + line.X - viewport_x,
+								line_y + tag.Shift,
+								old_tag_pos - 1, Math.Min (tag.Start + tag.Length, tag_pos) - 1,
+								text.ToString (), out text_size, tag.IsLink);
+
+						if (tag.IsLink) {
+							TextBoxBase.LinkRectangle link = new TextBoxBase.LinkRectangle (text_size);
+							link.LinkTag = tag;
+							owner.list_links.Add (link);
+						}
+					}
+					tag = tag.Next;
+				}
+
+				line.DrawEnding (g, line_y);
+				line_no++;
+			}
+		}
+
+		private int GetLineEnding (string line, int start, out LineEnding ending)
+		{
+			int res;
+			int rich_index;
+
+			if (start >= line.Length) {
+				ending = LineEnding.Wrap;
+				return -1;
+			}
+			
+			res = line.IndexOf ('\r', start);
+			rich_index = line.IndexOf ('\n', start);
+			
+			// Handle the case where we find both of them, and the \n is before the \r
+			if (res != -1 && rich_index != -1)
+				if (rich_index < res) {
+					ending = LineEnding.Rich;
+					return rich_index;				
+				}
+			
+			if (res != -1) {
+				if (res + 2 < line.Length && line [res + 1] == '\r' && line [res + 2] == '\n') {
+					ending = LineEnding.Soft;
+					return res;
+				}
+				if (res + 1 < line.Length && line [res + 1] == '\n') {
+					ending = LineEnding.Hard;
+					return res;
+				}
+				ending = LineEnding.Limp;
+				return res;
+			}
+
+			if (rich_index != -1) {
+				ending = LineEnding.Rich;
+				return rich_index;
+			}
+
+			ending = LineEnding.Wrap;
+			return line.Length;
+		}
+
+		// Get the line ending, but only of the types specified
+		private int GetLineEnding (string line, int start, out LineEnding ending, LineEnding type)
+		{
+			int index = start;
+			int last_length = 0;
+
+			do {
+				index = GetLineEnding (line, index + last_length, out ending);
+				last_length = LineEndingLength (ending);
+			} while 
+				((ending & type) != ending && index != -1);
+			
+			return index == -1 ? line.Length : index;
+		}
+		
+		internal int LineEndingLength (LineEnding ending)
+		{
+			switch (ending) {
+				case LineEnding.Limp:
+				case LineEnding.Rich:
+					return 1;
+				case LineEnding.Hard:
+					return 2;
+				case LineEnding.Soft:
+					return 3;
+			}
+
+			return 0;
+		}
+
+		internal string LineEndingToString (LineEnding ending)
+		{
+			switch (ending) {
+				case LineEnding.Limp:
+					return "\r";
+				case LineEnding.Hard:
+					return "\r\n";
+				case LineEnding.Soft:
+					return "\r\r\n";
+				case LineEnding.Rich:
+					return "\n";
+			}
+			
+			return string.Empty;
+		}
+
+		internal LineEnding StringToLineEnding (string ending)
+		{
+			switch (ending) {
+				case "\r":
+					return LineEnding.Limp;
+				case "\r\n":
+					return LineEnding.Hard;
+				case "\r\r\n":
+					return LineEnding.Soft;
+				case "\n":
+					return LineEnding.Rich;
+				default:
+					return LineEnding.None;
+			}
+		}
+		
+		internal void Insert (Line line, int pos, bool update_caret, string s)
+		{
+			Insert (line, pos, update_caret, s, line.FindTag (pos));
+		}
+
+		// Insert text at the given position; use formatting at insertion point for inserted text
+		internal void Insert (Line line, int pos, bool update_caret, string s, LineTag tag)
+		{
+			int break_index;
+			int base_line;
+			int old_line_count;
+			int count = 1;
+			LineEnding ending;
+			Line split_line;
+			
+			// Don't recalculate while we mess around
+			SuspendRecalc ();
+			
+			base_line = line.line_no;
+			old_line_count = lines;
+
+			// Discard chars after any possible -unlikely- end of file
+			int eof_index = s.IndexOf ('\0');
+			if (eof_index != -1)
+				s = s.Substring (0, eof_index);
+
+			break_index = GetLineEnding (s, 0, out ending, LineEnding.Hard | LineEnding.Rich);
+
+			// There are no line feeds in our text to be pasted
+			if (break_index == s.Length) {
+				line.InsertString (pos, s, tag);
+			} else {
+				// Add up to the first line feed to our current position
+				line.InsertString (pos, s.Substring (0, break_index + LineEndingLength (ending)), tag);
+				
+				// Split the rest of the original line to a new line
+				Split (line, pos + (break_index + LineEndingLength (ending)));
+				line.ending = ending;
+				break_index += LineEndingLength (ending);
+				split_line = GetLine (line.line_no + 1);
+				
+				// Insert brand new lines for any more line feeds in the inserted string
+				while (true) {
+					int next_break = GetLineEnding (s, break_index, out ending, LineEnding.Hard | LineEnding.Rich);
+					
+					if (next_break == s.Length)
+						break;
+						
+					string line_text = s.Substring (break_index, next_break - break_index +
+							LineEndingLength (ending));
+
+					Add (base_line + count, line_text, line.alignment, tag.Font, tag.Color, ending);
+
+					Line last = GetLine (base_line + count);
+					last.ending = ending;
+
+					count++;
+					break_index = next_break + LineEndingLength (ending);
+				}
+
+				// Add the remainder of the insert text to the split
+				// part of the original line
+				split_line.InsertString (0, s.Substring (break_index));
+			}
+			
+			// Allow the document to recalculate things
+			ResumeRecalc (false);
+
+			// Update our character count
+			CharCount += s.Length;
+
+			UpdateView (line, lines - old_line_count + 1, pos);
+
+			// Move the caret to the end of the inserted text if requested
+			if (update_caret) {
+				Line l = GetLine (line.line_no + lines - old_line_count);
+				PositionCaret (l, l.text.Length);
+				DisplayCaret ();
+			}
+		}
+
+		// Inserts a string at the given position
+		internal void InsertString (Line line, int pos, string s)
+		{
+			// Update our character count
+			CharCount += s.Length;
+
+			// Insert the text into the Line
+			line.InsertString (pos, s);
+		}
+
+		// Inserts a character at the current caret position
+		internal void InsertCharAtCaret (char ch, bool move_caret)
+		{
+			caret.line.InsertString (caret.pos, ch.ToString(), caret.tag);
+
+			// Update our character count
+			CharCount++;
+			
+			undo.RecordTyping (caret.line, caret.pos, ch);
+
+			UpdateView (caret.line, caret.pos);
+			
+			if (move_caret) {
+				caret.pos++;
+				UpdateCaret ();
+				SetSelectionToCaret (true);
+			}
+		}
+		
+		internal void InsertPicture (Line line, int pos, RTF.Picture picture)
+		{
+			//LineTag next_tag;
+			LineTag tag;
+			int len;
+
+			len = 1;
+
+			// Just a place holder basically
+			line.text.Insert (pos, "I");
+
+			PictureTag picture_tag = new PictureTag (line, pos + 1, picture);
+
+			tag = LineTag.FindTag (line, pos);
+			picture_tag.CopyFormattingFrom (tag);
+			/*next_tag = */tag.Break (pos + 1);
+			picture_tag.Previous = tag;
+			picture_tag.Next = tag.Next;
+			tag.Next = picture_tag;
+
+			//
+			// Picture tags need to be surrounded by text tags
+			//
+			if (picture_tag.Next == null) {
+				picture_tag.Next = new LineTag (line, pos + 1);
+				picture_tag.Next.CopyFormattingFrom (tag);
+				picture_tag.Next.Previous = picture_tag;
+			}
+
+			tag = picture_tag.Next;
+			while (tag != null) {
+				tag.Start += len;
+				tag = tag.Next;
+			}
+
+			line.Grow (len);
+			line.recalc = true;
+
+			UpdateView (line, pos);
+		}
+
+		internal void DeleteMultiline (Line start_line, int pos, int length)
+		{
+			Marker start = new Marker ();
+			Marker end = new Marker ();
+			int start_index = LineTagToCharIndex (start_line, pos);
+
+			start.line = start_line;
+			start.pos = pos;
+			start.tag = LineTag.FindTag (start_line, pos);
+
+			CharIndexToLineTag (start_index + length, out end.line,
+					out end.tag, out end.pos);
+
+			SuspendUpdate ();
+
+			if (start.line == end.line) {
+				DeleteChars (start.line, pos, end.pos - pos);
+			} else {
+
+				// Delete first and last lines
+				DeleteChars (start.line, start.pos, start.line.text.Length - start.pos);
+				DeleteChars (end.line, 0, end.pos);
+
+				int current = start.line.line_no + 1;
+				if (current < end.line.line_no) {
+					for (int i = end.line.line_no - 1; i >= current; i--) {
+						Delete (i);
+					}
+				}
+
+				// BIG FAT WARNING - selection_end.line might be stale due 
+				// to the above Delete() call. DONT USE IT before hitting the end of this method!
+
+				// Join start and end
+				Combine (start.line.line_no, current);
+			}
+
+			ResumeUpdate (true);
+		}
+
+		
+		// Deletes n characters at the given position; it will not delete past line limits
+		// pos is 0-based
+		public void DeleteChars (Line line, int pos, int count)
+		{
+			// Reduce our character count
+			CharCount -= count;
+			
+			line.DeleteCharacters (pos, count);
+
+			if (pos >= line.TextLengthWithoutEnding ()) {
+				LineEnding ending = line.ending;
+				GetLineEnding (line.text.ToString (), 0, out ending);
+				
+				if (ending != line.ending) {
+					line.ending = ending;
+
+					if (!multiline) {
+						UpdateView (line, lines, pos);
+						owner.Invalidate ();
+						return;
+					}
+				}
+			}
+			if (!multiline) {
+				UpdateView (line, lines, pos);
+				owner.Invalidate ();
+			} else 
+				UpdateView (line, pos);
+		}
+
+		// Deletes a character at or after the given position (depending on forward); it will not delete past line limits
+		public void DeleteChar (Line line, int pos, bool forward)
+		{
+			if ((pos == 0 && forward == false) || (pos == line.text.Length && forward == true))
+				return;
+			
+			undo.BeginUserAction ("Delete");
+
+			if (forward) {
+				undo.RecordDeleteString (line, pos, line, pos + 1);
+				DeleteChars (line, pos, 1);
+			} else {
+				undo.RecordDeleteString (line, pos - 1, line, pos);
+				DeleteChars (line, pos - 1, 1);
+			}
+
+			undo.EndUserAction ();
+		}
+
+		// Combine two lines
+		internal void Combine(int FirstLine, int SecondLine) {
+			Combine(GetLine(FirstLine), GetLine(SecondLine));
+		}
+
+		internal void Combine(Line first, Line second) {
+			LineTag	last;
+			int	shift;
+
+			// strip the ending off of the first lines text
+			first.text.Length = first.text.Length - LineEndingLength (first.ending);
+
+			// Combine the two tag chains into one
+			last = first.tags;
+
+			// Maintain the line ending style
+			first.ending = second.ending;
+
+			while (last.Next != null) {
+				last = last.Next;
+			}
+
+			// need to get the shift before setting the next tag since that effects length
+			shift = last.Start + last.Length - 1;
+			last.Next = second.tags;
+			last.Next.Previous = last;
+
+			// Fix up references within the chain
+			last = last.Next;
+			while (last != null) {
+				last.Line = first;
+				last.Start += shift;
+				last = last.Next;
+			}
+
+			// Combine both lines' strings
+			first.text.Insert(first.text.Length, second.text.ToString());
+			first.Grow(first.text.Length);
+
+			// Remove the reference to our (now combined) tags from the doomed line
+			second.tags = null;
+
+			// Renumber lines
+			DecrementLines(first.line_no + 2);	// first.line_no + 1 will be deleted, so we need to start renumbering one later
+
+			// Mop up
+			first.recalc = true;
+			first.height = 0;	// This forces RecalcDocument/UpdateView to redraw from this line on
+			first.Streamline(lines);
+
+			// Update Caret, Selection, etc
+			if (caret.line == second) {
+				caret.Combine(first, shift);
+			}
+			if (selection_anchor.line == second) {
+				selection_anchor.Combine(first, shift);
+			}
+			if (selection_start.line == second) {
+				selection_start.Combine(first, shift);
+			}
+			if (selection_end.line == second) {
+				selection_end.Combine(first, shift);
+			}
+
+			#if Debug
+				Line	check_first;
+				Line	check_second;
+
+				check_first = GetLine(first.line_no);
+				check_second = GetLine(check_first.line_no + 1);
+
+				Console.WriteLine("Pre-delete: Y of first line: {0}, second line: {1}", check_first.Y, check_second.Y);
+			#endif
+
+			this.Delete(second);
+
+			#if Debug
+				check_first = GetLine(first.line_no);
+				check_second = GetLine(check_first.line_no + 1);
+
+				Console.WriteLine("Post-delete Y of first line: {0}, second line: {1}", check_first.Y, check_second.Y);
+			#endif
+		}
+
+		// Split the line at the position into two
+		internal void Split(int LineNo, int pos) {
+			Line	line;
+			LineTag	tag;
+
+			line = GetLine(LineNo);
+			tag = LineTag.FindTag(line, pos);
+			Split(line, tag, pos);
+		}
+
+		internal void Split(Line line, int pos) {
+			LineTag	tag;
+
+			tag = LineTag.FindTag(line, pos);
+			Split(line, tag, pos);
+		}
+
+		///<summary>Split line at given tag and position into two lines</summary>
+		///if more space becomes available on previous line
+		internal void Split(Line line, LineTag tag, int pos) {
+			LineTag	new_tag;
+			Line	new_line;
+			bool	move_caret;
+			bool	move_sel_start;
+			bool	move_sel_end;
+
+			move_caret = false;
+			move_sel_start = false;
+			move_sel_end = false;
+
+#if DEBUG
+			SanityCheck();
+
+			if (tag.End < pos)
+				throw new Exception ("Split called with the wrong tag");
+#endif
+
+			// Adjust selection and cursors
+			if (caret.line == line && caret.pos >= pos) {
+				move_caret = true;
+			}
+			if (selection_start.line == line && selection_start.pos > pos) {
+				move_sel_start = true;
+			}
+
+			if (selection_end.line == line && selection_end.pos > pos) {
+				move_sel_end = true;
+			}
+
+			// cover the easy case first
+			if (pos == line.text.Length) {
+				Add (line.line_no + 1, String.Empty, line.alignment, tag.Font, tag.Color, line.ending);
+
+				new_line = GetLine (line.line_no + 1);
+				
+				if (move_caret) {
+					caret.line = new_line;
+					caret.tag = new_line.tags;
+					caret.pos = 0;
+
+					if (selection_visible == false) {
+						SetSelectionToCaret (true);
+					}
+				}
+
+				if (move_sel_start) {
+					selection_start.line = new_line;
+					selection_start.pos = 0;
+					selection_start.tag = new_line.tags;
+				}
+
+				if (move_sel_end) {
+					selection_end.line = new_line;
+					selection_end.pos = 0;
+					selection_end.tag = new_line.tags;
+				}
+
+#if DEBUG
+				SanityCheck ();
+#endif
+				return;
+			}
+
+			// We need to move the rest of the text into the new line
+			Add (line.line_no + 1, line.text.ToString (pos, line.text.Length - pos), line.alignment, tag.Font, tag.Color, line.ending);
+
+			// Now transfer our tags from this line to the next
+			new_line = GetLine(line.line_no + 1);
+
+			line.recalc = true;
+			new_line.recalc = true;
+
+			//make sure that if we are at the end of a tag, we start on the begining
+			//of a new one, if one exists... Stops us creating an empty tag and
+			//make the operation easier.
+			if (tag.Next != null && (tag.Next.Start - 1) == pos)
+				tag = tag.Next;
+
+			if ((tag.Start - 1) == pos) {
+				int	shift;
+
+				// We can simply break the chain and move the tag into the next line
+
+				// if the tag we are moving is the first, create an empty tag
+				// for the line we are leaving behind
+				if (tag == line.tags) {
+					new_tag = new LineTag(line, 1);
+					new_tag.CopyFormattingFrom (tag);
+					line.tags = new_tag;
+				}
+
+				if (tag.Previous != null) {
+					tag.Previous.Next = null;
+				}
+				new_line.tags = tag;
+				tag.Previous = null;
+				tag.Line = new_line;
+
+				// Walk the list and correct the start location of the tags we just bumped into the next line
+				shift = tag.Start - 1;
+
+				new_tag = tag;
+				while (new_tag != null) {
+					new_tag.Start -= shift;
+					new_tag.Line = new_line;
+					new_tag = new_tag.Next;
+				}
+			} else {
+				int	shift;
+
+				new_tag = new LineTag (new_line, 1);			
+				new_tag.Next = tag.Next;
+				new_tag.CopyFormattingFrom (tag);
+				new_line.tags = new_tag;
+				if (new_tag.Next != null) {
+					new_tag.Next.Previous = new_tag;
+				}
+				tag.Next = null;
+
+				shift = pos;
+				new_tag = new_tag.Next;
+				while (new_tag != null) {
+					new_tag.Start -= shift;
+					new_tag.Line = new_line;
+					new_tag = new_tag.Next;
+
+				}
+			}
+
+			if (move_caret) {
+				caret.line = new_line;
+				caret.pos = caret.pos - pos;
+				caret.tag = caret.line.FindTag(caret.pos);
+
+				if (selection_visible == false) {
+					SetSelectionToCaret (true);
+					move_sel_start = false;
+					move_sel_end = false;
+				}
+			}
+
+			if (move_sel_start) {
+				selection_start.line = new_line;
+				selection_start.pos = selection_start.pos - pos;
+				if  (selection_start.Equals(selection_end))
+					selection_start.tag = new_line.FindTag(selection_start.pos);
+				else
+					selection_start.tag = new_line.FindTag (selection_start.pos + 1);
+			}
+
+			if (move_sel_end) {
+				selection_end.line = new_line;
+				selection_end.pos = selection_end.pos - pos;
+				selection_end.tag = new_line.FindTag(selection_end.pos);
+			}
+
+			CharCount -= line.text.Length - pos;
+			line.text.Remove(pos, line.text.Length - pos);
+#if DEBUG
+			SanityCheck ();
+#endif
+		}
+
+#if DEBUG
+		private void SanityCheck () {
+			for (int i = 1; i < lines; i++) {
+				LineTag tag = GetLine (i).tags;
+
+				if (tag.Start != 1)
+					throw new Exception ("Line doesn't start at the begining");
+
+				int start = 1;
+				tag = tag.Next;
+
+				while (tag != null) {
+					if (tag.Start == start)
+						throw new Exception ("Empty tag!");
+
+					if (tag.Start < start)
+						throw new Exception ("Insane!!");
+
+					start = tag.Start;
+					tag = tag.Next;
+				}
+			}
+		}
+#endif
+
+		// Adds a line of text, with given font.
+		// Bumps any line at that line number that already exists down
+		internal void Add (int LineNo, string Text, Font font, Color color, LineEnding ending)
+		{
+			Add (LineNo, Text, alignment, font, color, ending);
+		}
+
+		internal void Add (int LineNo, string Text, HorizontalAlignment align, Font font, Color color, LineEnding ending)
+		{
+			Line	add;
+			Line	line;
+			int	line_no;
+
+			CharCount += Text.Length;
+
+			if (LineNo<1 || Text == null) {
+				if (LineNo<1) {
+					throw new ArgumentNullException("LineNo", "Line numbers must be positive");
+				} else {
+					throw new ArgumentNullException("Text", "Cannot insert NULL line");
+				}
+			}
+
+			add = new Line (this, LineNo, Text, align, font, color, ending);
+
+			line = document;
+			while (line != sentinel) {
+				add.parent = line;
+				line_no = line.line_no;
+
+				if (LineNo > line_no) {
+					line = line.right;
+				} else if (LineNo < line_no) {
+					line = line.left;
+				} else {
+					// Bump existing line numbers; walk all nodes to the right of this one and increment line_no
+					IncrementLines(line.line_no);
+					line = line.left;
+				}
+			}
+
+			add.left = sentinel;
+			add.right = sentinel;
+
+			if (add.parent != null) {
+				if (LineNo > add.parent.line_no) {
+					add.parent.right = add;
+				} else {
+					add.parent.left = add;
+				}
+			} else {
+				// Root node
+				document = add;
+			}
+
+			RebalanceAfterAdd(add);
+
+			lines++;
+		}
+
+		internal virtual void Clear() {
+			lines = 0;
+			CharCount = 0;
+			document = sentinel;
+		}
+
+		public virtual object Clone() {
+			Document clone;
+
+			clone = new Document(null);
+
+			clone.lines = this.lines;
+			clone.document = (Line)document.Clone();
+
+			return clone;
+		}
+
+		private void Delete (int LineNo)
+		{
+			Line	line;
+
+			if (LineNo > lines)
+				return;
+
+			line = GetLine (LineNo);
+
+			CharCount -= line.text.Length;
+
+			DecrementLines (LineNo + 1);
+			Delete (line);
+		}
+
+		private void Delete(Line line1) {
+			Line	line2;// = new Line();
+			Line	line3;
+
+			if ((line1.left == sentinel) || (line1.right == sentinel)) {
+				line3 = line1;
+			} else {
+				line3 = line1.right;
+				while (line3.left != sentinel) {
+					line3 = line3.left;
+				}
+			}
+
+			if (line3.left != sentinel) {
+				line2 = line3.left;
+			} else {
+				line2 = line3.right;
+			}
+
+			line2.parent = line3.parent;
+			if (line3.parent != null) {
+				if(line3 == line3.parent.left) {
+					line3.parent.left = line2;
+				} else {
+					line3.parent.right = line2;
+				}
+			} else {
+				document = line2;
+			}
+
+			if (line3 != line1) {
+				LineTag	tag;
+
+				if (selection_start.line == line3) {
+					selection_start.line = line1;
+				}
+
+				if (selection_end.line == line3) {
+					selection_end.line = line1;
+				}
+
+				if (selection_anchor.line == line3) {
+					selection_anchor.line = line1;
+				}
+
+				if (caret.line == line3) {
+					caret.line = line1;
+				}
+
+
+				line1.alignment = line3.alignment;
+				line1.ascent = line3.ascent;
+				line1.hanging_indent = line3.hanging_indent;
+				line1.height = line3.height;
+				line1.indent = line3.indent;
+				line1.line_no = line3.line_no;
+				line1.recalc = line3.recalc;
+				line1.right_indent = line3.right_indent;
+				line1.ending = line3.ending;
+				line1.space = line3.space;
+				line1.tags = line3.tags;
+				line1.text = line3.text;
+				line1.widths = line3.widths;
+				line1.offset = line3.offset;
+
+				tag = line1.tags;
+				while (tag != null) {
+					tag.Line = line1;
+					tag = tag.Next;
+				}
+			}
+
+			if (line3.color == LineColor.Black)
+				RebalanceAfterDelete(line2);
+
+			this.lines--;
+		}
+
+		// Invalidates the start line until the end of the viewstate
+		internal void InvalidateLinesAfter (Line start) {
+			owner.Invalidate (new Rectangle (0, start.Y - viewport_y, viewport_width, viewport_height - start.Y));
+		}
+
+		// Invalidate a section of the document to trigger redraw
+		internal void Invalidate(Line start, int start_pos, Line end, int end_pos) {
+			Line	l1;
+			Line	l2;
+			int	p1;
+			int	p2;
+
+			if ((start == end) && (start_pos == end_pos)) {
+				return;
+			}
+
+			if (end_pos == -1) {
+				end_pos = end.text.Length;
+			}
+	
+			// figure out what's before what so the logic below is straightforward
+			if (start.line_no < end.line_no) {
+				l1 = start;
+				p1 = start_pos;
+
+				l2 = end;
+				p2 = end_pos;
+			} else if (start.line_no > end.line_no) {
+				l1 = end;
+				p1 = end_pos;
+
+				l2 = start;
+				p2 = start_pos;
+			} else {
+				if (start_pos < end_pos) {
+					l1 = start;
+					p1 = start_pos;
+
+					l2 = end;
+					p2 = end_pos;
+				} else {
+					l1 = end;
+					p1 = end_pos;
+
+					l2 = start;
+					p2 = start_pos;
+				}
+
+				int endpoint = (int) l1.widths [p2];
+				if (p2 == l1.text.Length + 1) {
+					endpoint = (int) viewport_width;
+				}
+
+				#if Debug
+					Console.WriteLine("Invaliding backwards from {0}:{1} to {2}:{3}   {4}",
+							l1.line_no, p1, l2.line_no, p2,
+							new Rectangle(
+								(int)l1.widths[p1] + l1.X - viewport_x, 
+								l1.Y - viewport_y, 
+								(int)l1.widths[p2], 
+								l1.height
+								)
+						);
+				#endif
+
+				owner.Invalidate(new Rectangle (
+					offset_x + (int)l1.widths[p1] + l1.X - viewport_x, 
+					offset_y + l1.Y - viewport_y,
+					endpoint - (int) l1.widths [p1] + 1, 
+					l1.height));
+				return;
+			}
+
+			#if Debug
+				Console.WriteLine("Invaliding from {0}:{1} to {2}:{3} Start  => x={4}, y={5}, {6}x{7}", l1.line_no, p1, l2.line_no, p2, (int)l1.widths[p1] + l1.X - viewport_x, l1.Y - viewport_y, viewport_width, l1.height);
+				Console.WriteLine ("invalidate start line:  {0}  position:  {1}", l1.text, p1);
+			#endif
+
+			// Three invalidates:
+			// First line from start
+			owner.Invalidate(new Rectangle(
+				offset_x + (int)l1.widths[p1] + l1.X - viewport_x, 
+				offset_y + l1.Y - viewport_y, 
+				viewport_width, 
+				l1.height));
+
+			
+			// lines inbetween
+			if ((l1.line_no + 1) < l2.line_no) {
+				int	y;
+
+				y = GetLine(l1.line_no + 1).Y;
+				owner.Invalidate(new Rectangle(
+					offset_x, 
+					offset_y + y - viewport_y, 
+					viewport_width, 
+					l2.Y - y));
+
+				#if Debug
+					Console.WriteLine("Invaliding from {0}:{1} to {2}:{3} Middle => x={4}, y={5}, {6}x{7}", l1.line_no, p1, l2.line_no, p2, 0, y - viewport_y, viewport_width, l2.Y - y);
+				#endif
+			}
+			
+
+			// Last line to end
+			owner.Invalidate(new Rectangle(
+				offset_x + (int)l2.widths[0] + l2.X - viewport_x, 
+				offset_y + l2.Y - viewport_y, 
+				(int)l2.widths[p2] + 1, 
+				l2.height));
+
+			#if Debug
+				Console.WriteLine("Invaliding from {0}:{1} to {2}:{3} End    => x={4}, y={5}, {6}x{7}", l1.line_no, p1, l2.line_no, p2, (int)l2.widths[0] + l2.X - viewport_x, l2.Y - viewport_y, (int)l2.widths[p2] + 1, l2.height);
+			#endif
+		}
+
+		/// <summary>Select text around caret</summary>
+		internal void ExpandSelection(CaretSelection mode, bool to_caret) {
+			if (to_caret) {
+				// We're expanding the selection to the caret position
+				switch(mode) {
+					case CaretSelection.Line: {
+						// Invalidate the selection delta
+						if (caret > selection_prev) {
+							Invalidate(selection_prev.line, 0, caret.line, caret.line.text.Length);
+						} else {
+							Invalidate(selection_prev.line, selection_prev.line.text.Length, caret.line, 0);
+						}
+
+						if (caret.line.line_no <= selection_anchor.line.line_no) {
+							selection_start.line = caret.line;
+							selection_start.tag = caret.line.tags;
+							selection_start.pos = 0;
+
+							selection_end.line = selection_anchor.line;
+							selection_end.tag = selection_anchor.tag;
+							selection_end.pos = selection_anchor.pos;
+
+							selection_end_anchor = true;
+						} else {
+							selection_start.line = selection_anchor.line;
+							selection_start.pos = selection_anchor.height;
+							selection_start.tag = selection_anchor.line.FindTag(selection_anchor.height + 1);
+
+							selection_end.line = caret.line;
+							selection_end.tag = caret.line.tags;
+							selection_end.pos = caret.line.text.Length;
+
+							selection_end_anchor = false;
+						}
+						selection_prev.line = caret.line;
+						selection_prev.tag = caret.tag;
+						selection_prev.pos = caret.pos;
+
+						break;
+					}
+
+					case CaretSelection.Word: {
+						int	start_pos;
+						int	end_pos;
+
+						start_pos = FindWordSeparator(caret.line, caret.pos, false);
+						end_pos = FindWordSeparator(caret.line, caret.pos, true);
+
+						
+						// Invalidate the selection delta
+						if (caret > selection_prev) {
+							Invalidate(selection_prev.line, selection_prev.pos, caret.line, end_pos);
+						} else {
+							Invalidate(selection_prev.line, selection_prev.pos, caret.line, start_pos);
+						}
+						if (caret < selection_anchor) {
+							selection_start.line = caret.line;
+							selection_start.tag = caret.line.FindTag(start_pos + 1);
+							selection_start.pos = start_pos;
+
+							selection_end.line = selection_anchor.line;
+							selection_end.tag = selection_anchor.tag;
+							selection_end.pos = selection_anchor.pos;
+
+							selection_prev.line = caret.line;
+							selection_prev.tag = caret.tag;
+							selection_prev.pos = start_pos;
+
+							selection_end_anchor = true;
+						} else {
+							selection_start.line = selection_anchor.line;
+							selection_start.pos = selection_anchor.height;
+							selection_start.tag = selection_anchor.line.FindTag(selection_anchor.height + 1);
+
+							selection_end.line = caret.line;
+							selection_end.tag = caret.line.FindTag(end_pos);
+							selection_end.pos = end_pos;
+
+							selection_prev.line = caret.line;
+							selection_prev.tag = caret.tag;
+							selection_prev.pos = end_pos;
+
+							selection_end_anchor = false;
+						}
+						break;
+					}
+
+					case CaretSelection.Position: {
+						SetSelectionToCaret(false);
+						return;
+					}
+				}
+			} else {
+				// We're setting the selection 'around' the caret position
+				switch(mode) {
+					case CaretSelection.Line: {
+						this.Invalidate(caret.line, 0, caret.line, caret.line.text.Length);
+
+						selection_start.line = caret.line;
+						selection_start.tag = caret.line.tags;
+						selection_start.pos = 0;
+
+						selection_end.line = caret.line;
+						selection_end.pos = caret.line.text.Length;
+						selection_end.tag = caret.line.FindTag(selection_end.pos);
+
+						selection_anchor.line = selection_end.line;
+						selection_anchor.tag = selection_end.tag;
+						selection_anchor.pos = selection_end.pos;
+						selection_anchor.height = 0;
+
+						selection_prev.line = caret.line;
+						selection_prev.tag = caret.tag;
+						selection_prev.pos = caret.pos;
+
+						this.selection_end_anchor = true;
+
+						break;
+					}
+
+					case CaretSelection.Word: {
+						int	start_pos;
+						int	end_pos;
+
+						start_pos = FindWordSeparator(caret.line, caret.pos, false);
+						end_pos = FindWordSeparator(caret.line, caret.pos, true);
+
+						this.Invalidate(selection_start.line, start_pos, caret.line, end_pos);
+
+						selection_start.line = caret.line;
+						selection_start.tag = caret.line.FindTag(start_pos + 1);
+						selection_start.pos = start_pos;
+
+						selection_end.line = caret.line;
+						selection_end.tag = caret.line.FindTag(end_pos);
+						selection_end.pos = end_pos;
+
+						selection_anchor.line = selection_end.line;
+						selection_anchor.tag = selection_end.tag;
+						selection_anchor.pos = selection_end.pos;
+						selection_anchor.height = start_pos;
+
+						selection_prev.line = caret.line;
+						selection_prev.tag = caret.tag;
+						selection_prev.pos = caret.pos;
+
+						this.selection_end_anchor = true;
+
+						break;
+					}
+				}
+			}
+
+			SetSelectionVisible (!(selection_start == selection_end));
+		}
+
+		internal void SetSelectionToCaret(bool start) {
+			if (start) {
+				// Invalidate old selection; selection is being reset to empty
+				this.Invalidate(selection_start.line, selection_start.pos, selection_end.line, selection_end.pos);
+
+				selection_start.line = caret.line;
+				selection_start.tag = caret.tag;
+				selection_start.pos = caret.pos;
+
+				// start always also selects end
+				selection_end.line = caret.line;
+				selection_end.tag = caret.tag;
+				selection_end.pos = caret.pos;
+
+				selection_anchor.line = caret.line;
+				selection_anchor.tag = caret.tag;
+				selection_anchor.pos = caret.pos;
+			} else {
+				// Invalidate from previous end to caret (aka new end)
+				if (selection_end_anchor) {
+					if (selection_start != caret) {
+						this.Invalidate(selection_start.line, selection_start.pos, caret.line, caret.pos);
+					}
+				} else {
+					if (selection_end != caret) {
+						this.Invalidate(selection_end.line, selection_end.pos, caret.line, caret.pos);
+					}
+				}
+
+				if (caret < selection_anchor) {
+					selection_start.line = caret.line;
+					selection_start.tag = caret.tag;
+					selection_start.pos = caret.pos;
+
+					selection_end.line = selection_anchor.line;
+					selection_end.tag = selection_anchor.tag;
+					selection_end.pos = selection_anchor.pos;
+
+					selection_end_anchor = true;
+				} else {
+					selection_start.line = selection_anchor.line;
+					selection_start.tag = selection_anchor.tag;
+					selection_start.pos = selection_anchor.pos;
+
+					selection_end.line = caret.line;
+					selection_end.tag = caret.tag;
+					selection_end.pos = caret.pos;
+
+					selection_end_anchor = false;
+				}
+			}
+
+			SetSelectionVisible (!(selection_start == selection_end));
+		}
+
+		internal void SetSelection(Line start, int start_pos, Line end, int end_pos) {
+			if (selection_visible) {
+				Invalidate(selection_start.line, selection_start.pos, selection_end.line, selection_end.pos);
+			}
+
+			if ((end.line_no < start.line_no) || ((end == start) && (end_pos <= start_pos))) {
+				selection_start.line = end;
+				selection_start.tag = LineTag.FindTag(end, end_pos);
+				selection_start.pos = end_pos;
+
+				selection_end.line = start;
+				selection_end.tag = LineTag.FindTag(start, start_pos);
+				selection_end.pos = start_pos;
+
+				selection_end_anchor = true;
+			} else {
+				selection_start.line = start;
+				selection_start.tag = LineTag.FindTag(start, start_pos);
+				selection_start.pos = start_pos;
+
+				selection_end.line = end;
+				selection_end.tag = LineTag.FindTag(end, end_pos);
+				selection_end.pos = end_pos;
+
+				selection_end_anchor = false;
+			}
+
+			selection_anchor.line = start;
+			selection_anchor.tag = selection_start.tag;
+			selection_anchor.pos = start_pos;
+
+			if (((start == end) && (start_pos == end_pos)) || start == null || end == null) {
+				SetSelectionVisible (false);
+			} else {
+				SetSelectionVisible (true);
+				Invalidate(selection_start.line, selection_start.pos, selection_end.line, selection_end.pos);
+			}
+		}
+
+		internal void SetSelectionStart(Line start, int start_pos, bool invalidate) {
+			// Invalidate from the previous to the new start pos
+			if (invalidate)
+				Invalidate(selection_start.line, selection_start.pos, start, start_pos);
+
+			selection_start.line = start;
+			selection_start.pos = start_pos;
+			selection_start.tag = LineTag.FindTag(start, start_pos);
+
+			selection_anchor.line = start;
+			selection_anchor.pos = start_pos;
+			selection_anchor.tag = selection_start.tag;
+
+			selection_end_anchor = false;
+
+			
+			if ((selection_end.line != selection_start.line) || (selection_end.pos != selection_start.pos)) {
+				SetSelectionVisible (true);
+			} else {
+				SetSelectionVisible (false);
+			}
+
+			if (invalidate)
+				Invalidate(selection_start.line, selection_start.pos, selection_end.line, selection_end.pos);
+		}
+
+		internal void SetSelectionStart(int character_index, bool invalidate) {
+			Line	line;
+			LineTag	tag;
+			int	pos;
+
+			if (character_index < 0) {
+				return;
+			}
+
+			CharIndexToLineTag(character_index, out line, out tag, out pos);
+			SetSelectionStart(line, pos, invalidate);
+		}
+
+		internal void SetSelectionEnd(Line end, int end_pos, bool invalidate) {
+
+			if (end == selection_end.line && end_pos == selection_start.pos) {
+				selection_anchor.line = selection_start.line;
+				selection_anchor.tag = selection_start.tag;
+				selection_anchor.pos = selection_start.pos;
+
+				selection_end.line = selection_start.line;
+				selection_end.tag = selection_start.tag;
+				selection_end.pos = selection_start.pos;
+
+				selection_end_anchor = false;
+			} else if ((end.line_no < selection_anchor.line.line_no) || ((end == selection_anchor.line) && (end_pos <= selection_anchor.pos))) {
+				selection_start.line = end;
+				selection_start.tag = LineTag.FindTag(end, end_pos);
+				selection_start.pos = end_pos;
+
+				selection_end.line = selection_anchor.line;
+				selection_end.tag = selection_anchor.tag;
+				selection_end.pos = selection_anchor.pos;
+
+				selection_end_anchor = true;
+			} else {
+				selection_start.line = selection_anchor.line;
+				selection_start.tag = selection_anchor.tag;
+				selection_start.pos = selection_anchor.pos;
+
+				selection_end.line = end;
+				selection_end.tag = LineTag.FindTag(end, end_pos);
+				selection_end.pos = end_pos;
+
+				selection_end_anchor = false;
+			}
+
+			if ((selection_end.line != selection_start.line) || (selection_end.pos != selection_start.pos)) {
+				SetSelectionVisible (true);
+				if (invalidate)
+					Invalidate(selection_start.line, selection_start.pos, selection_end.line, selection_end.pos);
+			} else {
+				SetSelectionVisible (false);
+				// ?? Do I need to invalidate here, tests seem to work without it, but I don't think they should :-s
+			}
+		}
+
+		internal void SetSelectionEnd(int character_index, bool invalidate) {
+			Line	line;
+			LineTag	tag;
+			int	pos;
+
+			if (character_index < 0) {
+				return;
+			}
+
+			CharIndexToLineTag(character_index, out line, out tag, out pos);
+			SetSelectionEnd(line, pos, invalidate);
+		}
+
+		internal void SetSelection(Line start, int start_pos) {
+			if (selection_visible) {
+				Invalidate(selection_start.line, selection_start.pos, selection_end.line, selection_end.pos);
+			}
+
+			selection_start.line = start;
+			selection_start.pos = start_pos;
+			selection_start.tag = LineTag.FindTag(start, start_pos);
+
+			selection_end.line = start;
+			selection_end.tag = selection_start.tag;
+			selection_end.pos = start_pos;
+
+			selection_anchor.line = start;
+			selection_anchor.tag = selection_start.tag;
+			selection_anchor.pos = start_pos;
+
+			selection_end_anchor = false;
+			SetSelectionVisible (false);
+		}
+
+		internal void InvalidateSelectionArea() {
+			Invalidate (selection_start.line, selection_start.pos, selection_end.line, selection_end.pos);
+		}
+
+		// Return the current selection, as string
+		internal string GetSelection() {
+			// We return String.Empty if there is no selection
+			if ((selection_start.pos == selection_end.pos) && (selection_start.line == selection_end.line)) {
+				return string.Empty;
+			}
+
+			if (selection_start.line == selection_end.line) {
+				return selection_start.line.text.ToString (selection_start.pos, selection_end.pos - selection_start.pos);
+			} else {
+				StringBuilder	sb;
+				int		i;
+				int		start;
+				int		end;
+
+				sb = new StringBuilder();
+				start = selection_start.line.line_no;
+				end = selection_end.line.line_no;
+
+				sb.Append(selection_start.line.text.ToString(selection_start.pos, selection_start.line.text.Length - selection_start.pos));
+
+				if ((start + 1) < end) {
+					for (i = start + 1; i < end; i++) {
+						sb.Append(GetLine(i).text.ToString());
+					}
+				}
+
+				sb.Append(selection_end.line.text.ToString(0, selection_end.pos));
+
+				return sb.ToString();
+			}
+		}
+
+		internal void ReplaceSelection(string s, bool select_new) {
+			int		i;
+
+			int selection_start_pos = LineTagToCharIndex (selection_start.line, selection_start.pos);
+			SuspendRecalc ();
+
+			// First, delete any selected text
+			if ((selection_start.pos != selection_end.pos) || (selection_start.line != selection_end.line)) {
+				if (selection_start.line == selection_end.line) {
+					undo.RecordDeleteString (selection_start.line, selection_start.pos, selection_end.line, selection_end.pos);
+
+					DeleteChars (selection_start.line, selection_start.pos, selection_end.pos - selection_start.pos);
+
+					// The tag might have been removed, we need to recalc it
+					selection_start.tag = selection_start.line.FindTag(selection_start.pos + 1);
+				} else {
+					int		start;
+					int		end;
+
+					start = selection_start.line.line_no;
+					end = selection_end.line.line_no;
+
+					undo.RecordDeleteString (selection_start.line, selection_start.pos, selection_end.line, selection_end.pos);
+
+					InvalidateLinesAfter(selection_start.line);
+
+					// Delete first line
+					DeleteChars (selection_start.line, selection_start.pos, selection_start.line.text.Length - selection_start.pos);
+					selection_start.line.recalc = true;
+
+					// Delete last line
+					DeleteChars(selection_end.line, 0, selection_end.pos);
+
+					start++;
+					if (start < end) {
+						for (i = end - 1; i >= start; i--) {
+							Delete(i);
+						}
+					}
+
+					// BIG FAT WARNING - selection_end.line might be stale due 
+					// to the above Delete() call. DONT USE IT before hitting the end of this method!
+
+					// Join start and end
+					Combine(selection_start.line.line_no, start);
+				}
+			}
+
+
+			Insert(selection_start.line, selection_start.pos, false, s);
+			undo.RecordInsertString (selection_start.line, selection_start.pos, s);
+			ResumeRecalc (false);
+
+			Line begin_update_line = selection_start.line;
+			int begin_update_pos = selection_start.pos;
+			
+			if (!select_new) {
+				CharIndexToLineTag(selection_start_pos + s.Length, out selection_start.line,
+						out selection_start.tag, out selection_start.pos);
+
+				selection_end.line = selection_start.line;
+				selection_end.pos = selection_start.pos;
+				selection_end.tag = selection_start.tag;
+				selection_anchor.line = selection_start.line;
+				selection_anchor.pos = selection_start.pos;
+				selection_anchor.tag = selection_start.tag;
+
+				SetSelectionVisible (false);
+			} else {
+				CharIndexToLineTag(selection_start_pos, out selection_start.line,
+						out selection_start.tag, out selection_start.pos);
+
+				CharIndexToLineTag(selection_start_pos + s.Length, out selection_end.line,
+						out selection_end.tag, out selection_end.pos);
+
+				selection_anchor.line = selection_start.line;
+				selection_anchor.pos = selection_start.pos;
+				selection_anchor.tag = selection_start.tag;
+
+				SetSelectionVisible (true);
+			}
+
+			PositionCaret (selection_start.line, selection_start.pos);
+			UpdateView (begin_update_line, selection_end.line.line_no - begin_update_line.line_no, begin_update_pos);
+		}
+
+		internal void CharIndexToLineTag(int index, out Line line_out, out LineTag tag_out, out int pos) {
+			Line	line;
+			LineTag	tag;
+			int	i;
+			int	chars;
+			int	start;
+
+			chars = 0;
+
+			for (i = 1; i <= lines; i++) {
+				line = GetLine(i);
+
+				start = chars;
+				chars += line.text.Length;
+
+				if (index <= chars) {
+					// we found the line
+					tag = line.tags;
+
+					while (tag != null) {
+						if (index < (start + tag.Start + tag.Length - 1)) {
+							line_out = line;
+							tag_out = LineTag.GetFinalTag (tag);
+							pos = index - start;
+							return;
+						}
+						if (tag.Next == null) {
+							Line	next_line;
+
+							next_line = GetLine(line.line_no + 1);
+
+							if (next_line != null) {
+								line_out = next_line;
+								tag_out = LineTag.GetFinalTag (next_line.tags);
+								pos = 0;
+								return;
+							} else {
+								line_out = line;
+								tag_out = LineTag.GetFinalTag (tag);
+								pos = line_out.text.Length;
+								return;
+							}
+						}
+						tag = tag.Next;
+					}
+				}
+			}
+
+			line_out = GetLine(lines);
+			tag = line_out.tags;
+			while (tag.Next != null) {
+				tag = tag.Next;
+			}
+			tag_out = tag;
+			pos = line_out.text.Length;
+		}
+
+		internal int LineTagToCharIndex(Line line, int pos) {
+			int	i;
+			int	length;
+
+			// Count first and last line
+			length = 0;
+
+			// Count the lines in the middle
+
+			for (i = 1; i < line.line_no; i++) {
+				length += GetLine(i).text.Length;
+			}
+
+			length += pos;
+
+			return length;
+		}
+
+		internal int SelectionLength() {
+			if ((selection_start.pos == selection_end.pos) && (selection_start.line == selection_end.line)) {
+				return 0;
+			}
+
+			if (selection_start.line == selection_end.line) {
+				return selection_end.pos - selection_start.pos;
+			} else {
+				int	i;
+				int	start;
+				int	end;
+				int	length;
+
+				// Count first and last line
+				length = selection_start.line.text.Length - selection_start.pos + selection_end.pos + crlf_size;
+
+				// Count the lines in the middle
+				start = selection_start.line.line_no + 1;
+				end = selection_end.line.line_no;
+
+				if (start < end) {
+					for (i = start; i < end; i++) {
+						Line line = GetLine (i);
+						length += line.text.Length + LineEndingLength (line.ending);
+					}
+				}
+
+				return length;
+			}
+
+			
+		}
+
+
+		// UIA: Method used via reflection in TextRangeProvider
+
+		/// <summary>Give it a Line number and it returns the Line object at with that line number</summary>
+		internal Line GetLine(int LineNo) {
+			Line	line = document;
+
+			while (line != sentinel) {
+				if (LineNo == line.line_no) {
+					return line;
+				} else if (LineNo < line.line_no) {
+					line = line.left;
+				} else {
+					line = line.right;
+				}
+			}
+
+			return null;
+		}
+
+		/// <summary>Retrieve the previous tag; walks line boundaries</summary>
+		internal LineTag PreviousTag(LineTag tag) {
+			Line l; 
+
+			if (tag.Previous != null) {
+				return tag.Previous;
+			}
+
+			// Next line 
+			if (tag.Line.line_no == 1) {
+				return null;
+			}
+
+			l = GetLine(tag.Line.line_no - 1);
+			if (l != null) {
+				LineTag t;
+
+				t = l.tags;
+				while (t.Next != null) {
+					t = t.Next;
+				}
+				return t;
+			}
+
+			return null;
+		}
+
+		/// <summary>Retrieve the next tag; walks line boundaries</summary>
+		internal LineTag NextTag(LineTag tag) {
+			Line l;
+
+			if (tag.Next != null) {
+				return tag.Next;
+			}
+
+			// Next line
+			l = GetLine(tag.Line.line_no + 1);
+			if (l != null) {
+				return l.tags;
+			}
+
+			return null;
+		}
+
+		internal Line ParagraphStart(Line line) {
+			Line lastline = line;
+			do {
+				if (line.line_no <= 1)
+					break;
+
+				line = lastline;
+				lastline = GetLine (line.line_no - 1);
+			} while (lastline.ending == LineEnding.Wrap);
+
+			return line;
+		}       
+
+		internal Line ParagraphEnd(Line line) {
+			Line    l;
+   
+			while (line.ending == LineEnding.Wrap) {
+				l = GetLine(line.line_no + 1);
+				if ((l == null) || (l.ending != LineEnding.Wrap)) {
+					break;
+				}
+				line = l;
+			}
+			return line;
+		}
+
+		/// <summary>Give it a pixel offset coordinate and it returns the Line covering that are (offset
+		/// is either X or Y depending on if we are multiline
+		/// </summary>
+		internal Line GetLineByPixel (int offset, bool exact)
+		{
+			Line	line = document;
+			Line	last = null;
+
+			if (multiline) {
+				while (line != sentinel) {
+					last = line;
+					if ((offset >= line.Y) && (offset < (line.Y+line.height))) {
+						return line;
+					} else if (offset < line.Y) {
+						line = line.left;
+					} else {
+						line = line.right;
+					}
+				}
+			} else {
+				while (line != sentinel) {
+					last = line;
+					if ((offset >= line.X) && (offset < (line.X + line.Width)))
+						return line;
+					else if (offset < line.X)
+						line = line.left;
+					else
+						line = line.right;
+				}
+			}
+
+			if (exact) {
+				return null;
+			}
+			return last;
+		}
+
+		// UIA: Method used via reflection in TextProviderBehavior
+
+		// Give it x/y pixel coordinates and it returns the Tag at that position
+		internal LineTag FindCursor (int x, int y, out int index)
+		{
+			Line line;
+
+			x -= offset_x;
+			y -= offset_y;
+
+			line = GetLineByPixel (multiline ? y : x, false);
+
+			LineTag tag = line.GetTag (x);
+				
+			if (tag.Length == 0 && tag.Start == 1)
+				index = 0;
+			else
+				index = tag.GetCharIndex (x - line.align_shift);
+			
+			return tag;
+		}
+
+		/// <summary>Format area of document in specified font and color</summary>
+		/// <param name="start_pos">1-based start position on start_line</param>
+		/// <param name="end_pos">1-based end position on end_line </param>
+		internal void FormatText (Line start_line, int start_pos, Line end_line, int end_pos, Font font,
+				Color color, Color back_color, FormatSpecified specified)
+		{
+			Line    l;
+
+			// First, format the first line
+			if (start_line != end_line) {
+				// First line
+				LineTag.FormatText(start_line, start_pos, start_line.text.Length - start_pos + 1, font, color, back_color, specified);
+
+				// Format last line
+				LineTag.FormatText(end_line, 1, end_pos, font, color, back_color, specified);
+
+				// Now all the lines inbetween
+				for (int i = start_line.line_no + 1; i < end_line.line_no; i++) {
+					l = GetLine(i);
+					LineTag.FormatText(l, 1, l.text.Length, font, color, back_color, specified);
+				}
+			} else {
+				// Special case, single line
+				LineTag.FormatText(start_line, start_pos, end_pos - start_pos, font, color, back_color, specified);
+				
+				if ((end_pos - start_pos) == 0 && CaretTag.Length != 0)
+					CaretTag = CaretTag.Next;
+			}
+		}
+
+		internal void RecalculateAlignments ()
+		{
+			Line	line;
+			int	line_no;
+
+			line_no = 1;
+
+
+
+			while (line_no <= lines) {
+				line = GetLine(line_no);
+
+				if (line != null) {
+					switch (line.alignment) {
+					case HorizontalAlignment.Left:
+						line.align_shift = 0;
+						break;
+					case HorizontalAlignment.Center:
+ 						line.align_shift = (viewport_width - (int)line.widths[line.text.Length]) / 2;
+						break;
+					case HorizontalAlignment.Right:
+ 						line.align_shift = viewport_width - (int)line.widths[line.text.Length] - right_margin;
+						break;
+					}
+				}
+
+				line_no++;
+			}
+			return;
+		}
+
+		/// <summary>Calculate formatting for the whole document</summary>
+		internal bool RecalculateDocument(Graphics g) {
+			return RecalculateDocument(g, 1, this.lines, false);
+		}
+
+		/// <summary>Calculate formatting starting at a certain line</summary>
+		internal bool RecalculateDocument(Graphics g, int start) {
+			return RecalculateDocument(g, start, this.lines, false);
+		}
+
+		/// <summary>Calculate formatting within two given line numbers</summary>
+		internal bool RecalculateDocument(Graphics g, int start, int end) {
+			return RecalculateDocument(g, start, end, false);
+		}
+
+		/// <summary>With optimize on, returns true if line heights changed</summary>
+		internal bool RecalculateDocument(Graphics g, int start, int end, bool optimize) {
+			Line	line;
+			int	line_no;
+			int	offset;
+			int	new_width;
+			bool	changed;
+			int	shift;
+
+			if (recalc_suspended > 0) {
+				recalc_pending = true;
+				recalc_start = Math.Min (recalc_start, start);
+				recalc_end = Math.Max (recalc_end, end);
+				recalc_optimize = optimize;
+				return false;
+			}
+
+			// Fixup the positions, they can go kinda nuts
+			// (this is suspend and resume recalc - they set them to 1 and max)
+			start = Math.Max (start, 1);
+			end = Math.Min (end, lines);
+
+			offset = GetLine(start).offset;
+			line_no = start;
+			new_width = 0;
+			shift = this.lines;
+			if (!optimize) {
+				changed = true;		// We always return true if we run non-optimized
+			} else {
+				changed = false;
+			}
+
+			while (line_no <= (end + this.lines - shift)) {
+				line = GetLine(line_no++);
+				line.offset = offset;
+
+				// if we are not calculating a password
+				if (!calc_pass) {
+					if (!optimize) {
+						line.RecalculateLine(g, this);
+					} else {
+						if (line.recalc && line.RecalculateLine(g, this)) {
+							changed = true;
+							// If the height changed, all subsequent lines change
+							end = this.lines;
+							shift = this.lines;
+						}
+					}
+				} else {
+					if (!optimize) {
+						line.RecalculatePasswordLine(g, this);
+					} else {
+						if (line.recalc && line.RecalculatePasswordLine(g, this)) {
+							changed = true;
+							// If the height changed, all subsequent lines change
+							end = this.lines;
+							shift = this.lines;
+						}
+					}
+				}
+
+				if (line.widths[line.text.Length] > new_width) {
+					new_width = (int)line.widths[line.text.Length];
+				}
+
+				// Calculate alignment
+				if (line.alignment != HorizontalAlignment.Left) {
+					if (line.alignment == HorizontalAlignment.Center) {
+						line.align_shift = (viewport_width - (int)line.widths[line.text.Length]) / 2;
+					} else {
+						line.align_shift = viewport_width - (int)line.widths[line.text.Length] - 1;
+					}
+				}
+
+				if (multiline)
+					offset += line.height;
+				else
+					offset += (int) line.widths [line.text.Length];
+
+				if (line_no > lines) {
+					break;
+				}
+			}
+
+			if (document_x != new_width) {
+				document_x = new_width;
+				if (WidthChanged != null) {
+					WidthChanged(this, null);
+				}
+			}
+
+			RecalculateAlignments();
+
+			line = GetLine(lines);
+
+			if (document_y != line.Y + line.height) {
+				document_y = line.Y + line.height;
+				if (HeightChanged != null) {
+					HeightChanged(this, null);
+				}
+			}
+
+			// scan for links and tell us if its all
+			// changed, so we can update everything
+			if (EnableLinks)
+				ScanForLinks (start, end, ref changed);
+
+			UpdateCaret();
+			return changed;
+		}
+
+		internal int Size() {
+			return lines;
+		}
+
+		private void owner_HandleCreated(object sender, EventArgs e) {
+			RecalculateDocument(owner.CreateGraphicsInternal());
+			AlignCaret();
+		}
+
+		private void owner_VisibleChanged(object sender, EventArgs e) {
+			if (owner.Visible) {
+				RecalculateDocument(owner.CreateGraphicsInternal());
+			}
+		}
+
+		internal static bool IsWordSeparator (char ch)
+		{
+			switch (ch) {
+			case ' ':
+			case '\t':
+			case '(':
+			case ')':
+			case '\r':
+			case '\n':
+				return true;
+			default:
+				return false;
+			}
+		}
+
+		internal int FindWordSeparator(Line line, int pos, bool forward) {
+			int len;
+
+			len = line.text.Length;
+
+			if (forward) {
+				for (int i = pos + 1; i < len; i++) {
+					if (IsWordSeparator(line.Text[i])) {
+						return i + 1;
+					}
+				}
+				return len;
+			} else {
+				for (int i = pos - 1; i > 0; i--) {
+					if (IsWordSeparator(line.Text[i - 1])) {
+						return i;
+					}
+				}
+				return 0;
+			}
+		}
+
+		/* Search document for text */
+		internal bool FindChars(char[] chars, Marker start, Marker end, out Marker result) {
+			Line	line;
+			int	line_no;
+			int	pos;
+			int	line_len;
+
+			// Search for occurence of any char in the chars array
+			result = new Marker();
+
+			line = start.line;
+			line_no = start.line.line_no;
+			pos = start.pos;
+			while (line_no <= end.line.line_no) {
+				line_len = line.text.Length;
+				while (pos < line_len) {
+					for (int i = 0; i < chars.Length; i++) {
+						if (line.text[pos] == chars[i]) {
+							// Special case
+							if ((line.line_no == end.line.line_no) && (pos >= end.pos)) {
+								return false;
+							}
+
+							result.line = line;
+							result.pos = pos;
+							return true;
+						}
+					}
+					pos++;
+				}
+
+				pos = 0;
+				line_no++;
+				line = GetLine(line_no);
+			}
+
+			return false;
+		}
+
+		// This version does not build one big string for searching, instead it handles 
+		// line-boundaries, which is faster and less memory intensive
+		// FIXME - Depending on culture stuff we might have to create a big string and use culturespecific 
+		// search stuff and change it to accept and return positions instead of Markers (which would match 
+		// RichTextBox behaviour better but would be inconsistent with the rest of TextControl)
+		internal bool Find(string search, Marker start, Marker end, out Marker result, RichTextBoxFinds options) {
+			Marker	last;
+			string	search_string;
+			Line	line;
+			int	line_no;
+			int	pos;
+			int	line_len;
+			int	current;
+			bool	word;
+			bool	word_option;
+			bool	ignore_case;
+			bool	reverse;
+			char	c;
+
+			result = new Marker();
+			word_option = ((options & RichTextBoxFinds.WholeWord) != 0);
+			ignore_case = ((options & RichTextBoxFinds.MatchCase) == 0);
+			reverse = ((options & RichTextBoxFinds.Reverse) != 0);
+
+			line = start.line;
+			line_no = start.line.line_no;
+			pos = start.pos;
+			current = 0;
+
+			// Prep our search string, lowercasing it if we do case-independent matching
+			if (ignore_case) {
+				StringBuilder	sb;
+				sb = new StringBuilder(search);
+				for (int i = 0; i < sb.Length; i++) {
+					sb[i] = Char.ToLower(sb[i]);
+				}
+				search_string = sb.ToString();
+			} else {
+				search_string = search;
+			}
+
+			// We need to check if the character before our start position is a wordbreak
+			if (word_option) {
+				if (line_no == 1) {
+					if ((pos == 0) || (IsWordSeparator(line.text[pos - 1]))) {
+						word = true;
+					} else {
+						word = false;
+					}
+				} else {
+					if (pos > 0) {
+						if (IsWordSeparator(line.text[pos - 1])) {
+							word = true;
+						} else {
+							word = false;
+						}
+					} else {
+						// Need to check the end of the previous line
+						Line	prev_line;
+
+						prev_line = GetLine(line_no - 1);
+						if (prev_line.ending == LineEnding.Wrap) {
+							if (IsWordSeparator(prev_line.text[prev_line.text.Length - 1])) {
+								word = true;
+							} else {
+								word = false;
+							}
+						} else {
+							word = true;
+						}
+					}
+				}
+			} else {
+				word = false;
+			}
+
+			// To avoid duplication of this loop with reverse logic, we search
+			// through the document, remembering the last match and when returning
+			// report that last remembered match
+
+			last = new Marker();
+			last.height = -1;	// Abused - we use it to track change
+
+			while (line_no <= end.line.line_no) {
+				if (line_no != end.line.line_no) {
+					line_len = line.text.Length;
+				} else {
+					line_len = end.pos;
+				}
+
+				while (pos < line_len) {
+
+					if (word_option && (current == search_string.Length)) {
+						if (IsWordSeparator(line.text[pos])) {
+							if (!reverse) {
+								goto FindFound;
+							} else {
+								last = result;
+								current = 0;
+							}
+						} else {
+							current = 0;
+						}
+					}
+
+					if (ignore_case) {
+						c = Char.ToLower(line.text[pos]);
+					} else {
+						c = line.text[pos];
+					}
+
+					if (c == search_string[current]) {
+						
+						if (current == 0) {
+							result.line = line;
+							result.pos = pos;
+						}
+						if (!word_option || (word_option && (word || (current > 0)))) {
+							current++;
+						}
+
+						if (!word_option && (current == search_string.Length)) {
+							if (!reverse) {
+								goto FindFound;
+							} else {
+								last = result;
+								current = 0;
+							}
+						}
+					} else {
+						current = 0;
+					}
+					pos++;
+
+					if (!word_option) {
+						continue;
+					}
+
+					if (IsWordSeparator(c)) {
+						word = true;
+					} else {
+						word = false;
+					}
+				}
+
+				if (word_option) {
+					// Mark that we just saw a word boundary
+					if (line.ending != LineEnding.Wrap || line.line_no == lines - 1) {
+						word = true;
+					}
+
+					if (current == search_string.Length) {
+						if (word) {
+							if (!reverse) {
+								goto FindFound;
+							} else {
+								last = result;
+								current = 0;
+							}
+						} else {
+							current = 0;
+						}
+					}
+				}
+
+				pos = 0;
+				line_no++;
+				line = GetLine(line_no);
+			}
+
+			if (reverse) {
+				if (last.height != -1) {
+					result = last;
+					return true;
+				}
+			}
+
+			return false;
+
+			FindFound:
+			if (!reverse) {
+//				if ((line.line_no == end.line.line_no) && (pos >= end.pos)) {
+//					return false;
+//				}
+				return true;
+			}
+
+			result = last;
+			return true;
+
+		}
+
+		/* Marker stuff */
+		internal void GetMarker(out Marker mark, bool start) {
+			mark = new Marker();
+
+			if (start) {
+				mark.line = GetLine(1);
+				mark.tag = mark.line.tags;
+				mark.pos = 0;
+			} else {
+				mark.line = GetLine(lines);
+				mark.tag = mark.line.tags;
+				while (mark.tag.Next != null) {
+					mark.tag = mark.tag.Next;
+				}
+				mark.pos = mark.line.text.Length;
+			}
+		}
+		#endregion	// Internal Methods
+
+		#region Events
+		internal event EventHandler CaretMoved;
+		internal event EventHandler WidthChanged;
+		internal event EventHandler HeightChanged;
+		internal event EventHandler LengthChanged;
+		internal event EventHandler UIASelectionChanged;
+		#endregion	// Events
+
+		#region Administrative
+		public IEnumerator GetEnumerator() {
+			// FIXME
+			return null;
+		}
+
+		public override bool Equals(object obj) {
+			if (obj == null) {
+				return false;
+			}
+
+			if (!(obj is Document)) {
+				return false;
+			}
+
+			if (obj == this) {
+				return true;
+			}
+
+			if (ToString().Equals(((Document)obj).ToString())) {
+				return true;
+			}
+
+			return false;
+		}
+
+		public override int GetHashCode() {
+			return document_id;
+		}
+
+		public override string ToString() {
+			return "document " + this.document_id;
+		}
+		#endregion	// Administrative
+	}
+
+	internal class PictureTag : LineTag {
+
+		internal RTF.Picture picture;
+
+		internal PictureTag (Line line, int start, RTF.Picture picture) : base (line, start)
+		{
+			this.picture = picture;
+		}
+
+		public override bool IsTextTag {
+			get { return false; }
+		}
+
+		public override SizeF SizeOfPosition (Graphics dc, int pos)
+		{
+			return picture.Size;
+		}
+
+		internal override int MaxHeight ()
+		{
+			return (int) (picture.Height + 0.5F);
+		}
+
+		public override void Draw (Graphics dc, Color color, float xoff, float y, int start, int end)
+		{
+			picture.DrawImage (dc, xoff + Line.widths [start], y, false);
+		}
+
+		public override void Draw (Graphics dc, Color color, float xoff, float y, int start, int end, string text)
+		{
+			picture.DrawImage (dc, xoff + + Line.widths [start], y, false);
+		}
+
+		public override string Text ()
+		{
+			return "I";
+		}
+	}
+
+	internal class UndoManager {
+
+		internal enum ActionType {
+
+			Typing,
+
+			// This is basically just cut & paste
+			InsertString,
+			DeleteString,
+
+			UserActionBegin,
+			UserActionEnd
+		}
+
+		internal class Action {
+			internal ActionType	type;
+			internal int		line_no;
+			internal int		pos;
+			internal object		data;
+		}
+
+		#region Local Variables
+		private Document	document;
+		private Stack		undo_actions;
+		private Stack		redo_actions;
+
+		//private int		caret_line;
+		//private int		caret_pos;
+
+		// When performing an action, we lock the queue, so that the action can't be undone
+		private bool locked;
+		#endregion	// Local Variables
+
+		#region Constructors
+		internal UndoManager (Document document)
+		{
+			this.document = document;
+			undo_actions = new Stack (50);
+			redo_actions = new Stack (50);
+		}
+		#endregion	// Constructors
+
+		#region Properties
+		internal bool CanUndo {
+			get { return undo_actions.Count > 0; }
+		}
+
+		internal bool CanRedo {
+			get { return redo_actions.Count > 0; }
+		}
+
+		internal string UndoActionName {
+			get {
+				foreach (Action action in undo_actions) {
+					if (action.type == ActionType.UserActionBegin)
+						return (string) action.data;
+					if (action.type == ActionType.Typing)
+						return String.Format ("Typing");
+				}
+				return String.Empty;
+			}
+		}
+
+		internal string RedoActionName {
+			get {
+				foreach (Action action in redo_actions) {
+					if (action.type == ActionType.UserActionBegin)
+						return (string) action.data;
+					if (action.type == ActionType.Typing)
+						return String.Format ("Typing");
+				}
+				return String.Empty;
+			}
+		}
+		#endregion	// Properties
+
+		#region Internal Methods
+		internal void Clear ()
+		{
+			undo_actions.Clear();
+			redo_actions.Clear();
+		}
+
+		internal bool Undo ()
+		{
+			Action action;
+			bool user_action_finished = false;
+
+			if (undo_actions.Count == 0)
+				return false;
+
+			locked = true;
+			do {
+				Line start;
+				action = (Action) undo_actions.Pop ();
+
+				// Put onto redo stack
+				redo_actions.Push(action);
+
+				// Do the thing
+				switch(action.type) {
+
+				case ActionType.UserActionBegin:
+					user_action_finished = true;
+					break;
+
+				case ActionType.UserActionEnd:
+					// noop
+					break;
+
+				case ActionType.InsertString:
+					start = document.GetLine (action.line_no);
+					document.SuspendUpdate ();
+					document.DeleteMultiline (start, action.pos, ((string) action.data).Length + 1);
+					document.PositionCaret (start, action.pos);
+					document.SetSelectionToCaret (true);
+					document.ResumeUpdate (true);
+					break;
+
+				case ActionType.Typing:
+					start = document.GetLine (action.line_no);
+					document.SuspendUpdate ();
+					document.DeleteMultiline (start, action.pos, ((StringBuilder) action.data).Length);
+					document.PositionCaret (start, action.pos);
+					document.SetSelectionToCaret (true);
+					document.ResumeUpdate (true);
+
+					// This is an open ended operation, so only a single typing operation can be undone at once
+					user_action_finished = true;
+					break;
+
+				case ActionType.DeleteString:
+					start = document.GetLine (action.line_no);
+					document.SuspendUpdate ();
+					Insert (start, action.pos, (Line) action.data, true);
+					document.ResumeUpdate (true);
+					break;
+				}
+			} while (!user_action_finished && undo_actions.Count > 0);
+
+			locked = false;
+
+			return true;
+		}
+
+		internal bool Redo ()
+		{
+			Action action;
+			bool user_action_finished = false;
+
+			if (redo_actions.Count == 0)
+				return false;
+
+			locked = true;
+			do {
+				Line start;
+				int start_index;
+
+				action = (Action) redo_actions.Pop ();
+				undo_actions.Push (action);
+
+				switch (action.type) {
+
+				case ActionType.UserActionBegin:
+					//  Noop
+					break;
+
+				case ActionType.UserActionEnd:
+					user_action_finished = true;
+					break;
+
+				case ActionType.InsertString:
+					start = document.GetLine (action.line_no);
+					document.SuspendUpdate ();
+					start_index = document.LineTagToCharIndex (start, action.pos);
+					document.InsertString (start, action.pos, (string) action.data);
+					document.CharIndexToLineTag (start_index + ((string) action.data).Length,
+							out document.caret.line, out document.caret.tag,
+							out document.caret.pos);
+					document.UpdateCaret ();
+					document.SetSelectionToCaret (true);
+					document.ResumeUpdate (true);
+					break;
+
+				case ActionType.Typing:
+					start = document.GetLine (action.line_no);
+					document.SuspendUpdate ();
+					start_index = document.LineTagToCharIndex (start, action.pos);
+					document.InsertString (start, action.pos, ((StringBuilder) action.data).ToString ());
+					document.CharIndexToLineTag (start_index + ((StringBuilder) action.data).Length,
+							out document.caret.line, out document.caret.tag,
+							out document.caret.pos);
+					document.UpdateCaret ();
+					document.SetSelectionToCaret (true);
+					document.ResumeUpdate (true);
+
+					// This is an open ended operation, so only a single typing operation can be undone at once
+					user_action_finished = true;
+					break;
+
+				case ActionType.DeleteString:
+					start = document.GetLine (action.line_no);
+					document.SuspendUpdate ();
+					document.DeleteMultiline (start, action.pos, ((Line) action.data).text.Length);
+					document.PositionCaret (start, action.pos);
+					document.SetSelectionToCaret (true);
+					document.ResumeUpdate (true);
+
+					break;
+				}
+			} while (!user_action_finished && redo_actions.Count > 0);
+
+			locked = false;
+
+			return true;
+		}
+		#endregion	// Internal Methods
+
+		#region Private Methods
+
+		public void BeginUserAction (string name)
+		{
+			if (locked)
+				return;
+
+			// Nuke the redo queue
+			redo_actions.Clear ();
+
+			Action ua = new Action ();
+			ua.type = ActionType.UserActionBegin;
+			ua.data = name;
+
+			undo_actions.Push (ua);
+		}
+
+		public void EndUserAction ()
+		{
+			if (locked)
+				return;
+
+			Action ua = new Action ();
+			ua.type = ActionType.UserActionEnd;
+
+			undo_actions.Push (ua);
+		}
+
+		// start_pos, end_pos = 1 based
+		public void RecordDeleteString (Line start_line, int start_pos, Line end_line, int end_pos)
+		{
+			if (locked)
+				return;
+
+			// Nuke the redo queue
+			redo_actions.Clear ();
+
+			Action	a = new Action ();
+
+			// We cant simply store the string, because then formatting would be lost
+			a.type = ActionType.DeleteString;
+			a.line_no = start_line.line_no;
+			a.pos = start_pos;
+			a.data = Duplicate (start_line, start_pos, end_line, end_pos);
+
+			undo_actions.Push(a);
+		}
+
+		public void RecordInsertString (Line line, int pos, string str)
+		{
+			if (locked || str.Length == 0)
+				return;
+
+			// Nuke the redo queue
+			redo_actions.Clear ();
+
+			Action a = new Action ();
+
+			a.type = ActionType.InsertString;
+			a.data = str;
+			a.line_no = line.line_no;
+			a.pos = pos;
+
+			undo_actions.Push (a);
+		}
+
+		public void RecordTyping (Line line, int pos, char ch)
+		{
+			if (locked)
+				return;
+
+			// Nuke the redo queue
+			redo_actions.Clear ();
+
+			Action a = null;
+
+			if (undo_actions.Count > 0)
+				a = (Action) undo_actions.Peek ();
+
+			if (a == null || a.type != ActionType.Typing) {
+				a = new Action ();
+				a.type = ActionType.Typing;
+				a.data = new StringBuilder ();
+				a.line_no = line.line_no;
+				a.pos = pos;
+
+				undo_actions.Push (a);
+			}
+
+			StringBuilder data = (StringBuilder) a.data;
+			data.Append (ch);
+		}
+
+		// start_pos = 1-based
+		// end_pos = 1-based
+		public Line Duplicate(Line start_line, int start_pos, Line end_line, int end_pos)
+		{
+			Line	ret;
+			Line	line;
+			Line	current;
+			LineTag	tag;
+			LineTag	current_tag;
+			int	start;
+			int	end;
+			int	tag_start;
+
+			line = new Line (start_line.document, start_line.ending);
+			ret = line;
+
+			for (int i = start_line.line_no; i <= end_line.line_no; i++) {
+				current = document.GetLine(i);
+
+				if (start_line.line_no == i) {
+					start = start_pos;
+				} else {
+					start = 0;
+				}
+
+				if (end_line.line_no == i) {
+					end = end_pos;
+				} else {
+					end = current.text.Length;
+				}
+
+				if (end_pos == 0)
+					continue;
+
+				// Text for the tag
+				line.text = new StringBuilder (current.text.ToString (start, end - start));
+
+				// Copy tags from start to start+length onto new line
+				current_tag = current.FindTag (start + 1);
+				while ((current_tag != null) && (current_tag.Start <= end)) {
+					if ((current_tag.Start <= start) && (start < (current_tag.Start + current_tag.Length))) {
+						// start tag is within this tag
+						tag_start = start;
+					} else {
+						tag_start = current_tag.Start;
+					}
+
+					tag = new LineTag(line, tag_start - start + 1);
+					tag.CopyFormattingFrom (current_tag);
+
+					current_tag = current_tag.Next;
+
+					// Add the new tag to the line
+					if (line.tags == null) {
+						line.tags = tag;
+					} else {
+						LineTag tail;
+						tail = line.tags;
+
+						while (tail.Next != null) {
+							tail = tail.Next;
+						}
+						tail.Next = tag;
+						tag.Previous = tail;
+					}
+				}
+
+				if ((i + 1) <= end_line.line_no) {
+					line.ending = current.ending;
+
+					// Chain them (we use right/left as next/previous)
+					line.right = new Line (start_line.document, start_line.ending);
+					line.right.left = line;
+					line = line.right;
+				}
+			}
+
+			return ret;
+		}
+
+		// Insert multi-line text at the given position; use formatting at insertion point for inserted text
+		internal void Insert(Line line, int pos, Line insert, bool select)
+		{
+			Line	current;
+			LineTag	tag;
+			int	offset;
+			int	lines;
+			Line	first;
+
+			// Handle special case first
+			if (insert.right == null) {
+
+				// Single line insert
+				document.Split(line, pos);
+
+				if (insert.tags == null) {
+					return;	// Blank line
+				}
+
+				//Insert our tags at the end
+				tag = line.tags;
+
+				while (tag.Next != null) {
+					tag = tag.Next;
+				}
+
+				offset = tag.Start + tag.Length - 1;
+
+				tag.Next = insert.tags;
+				line.text.Insert(offset, insert.text.ToString());
+
+				// Adjust start locations
+				tag = tag.Next;
+				while (tag != null) {
+					tag.Start += offset;
+					tag.Line = line;
+					tag = tag.Next;
+				}
+				// Put it back together
+				document.Combine(line.line_no, line.line_no + 1);
+
+				if (select) {
+					document.SetSelectionStart (line, pos, false);
+					document.SetSelectionEnd (line, pos + insert.text.Length, false);
+				}
+
+				document.UpdateView(line, pos);
+				return;
+			}
+
+			first = line;
+			lines = 1;
+			current = insert;
+
+			while (current != null) {
+
+				if (current == insert) {
+					// Inserting the first line we split the line (and make space)
+					document.Split(line.line_no, pos);
+					//Insert our tags at the end of the line
+					tag = line.tags;
+
+					
+					if (tag != null && tag.Length != 0) {
+						while (tag.Next != null) {
+							tag = tag.Next;
+						}
+						offset = tag.Start + tag.Length - 1;
+						tag.Next = current.tags;
+						tag.Next.Previous = tag;
+
+						tag = tag.Next;
+
+					} else {
+						offset = 0;
+						line.tags = current.tags;
+						line.tags.Previous = null;
+						tag = line.tags;
+					}
+
+					line.ending = current.ending;
+				} else {
+					document.Split(line.line_no, 0);
+					offset = 0;
+					line.tags = current.tags;
+					line.tags.Previous = null;
+					line.ending = current.ending;
+					tag = line.tags;
+				}
+
+				// Adjust start locations and line pointers
+				while (tag != null) {
+					tag.Start += offset - 1;
+					tag.Line = line;
+					tag = tag.Next;
+				}
+
+				line.text.Insert(offset, current.text.ToString());
+				line.Grow(line.text.Length);
+
+				line.recalc = true;
+				line = document.GetLine(line.line_no + 1);
+
+				// FIXME? Test undo of line-boundaries
+				if ((current.right == null) && (current.tags.Length != 0)) {
+					document.Combine(line.line_no - 1, line.line_no);
+				}
+				current = current.right;
+				lines++;
+
+			}
+
+			// Recalculate our document
+			document.UpdateView(first, lines, pos);
+			return;
+		}		
+		#endregion	// Private Methods
+	}
+}