1 files changed, 44 insertions, 10 deletions

diff --git a/main/src/core/Mono.Texteditor/Mono.TextEditor/TextEditorData.cs b/main/src/core/Mono.Texteditor/Mono.TextEditor/TextEditorData.cs
index a9c9e75adc..599ba88014 100644
--- a/main/src/core/Mono.Texteditor/Mono.TextEditor/TextEditorData.cs
+++ b/main/src/core/Mono.Texteditor/Mono.TextEditor/TextEditorData.cs
@@ -95,7 +95,7 @@ namespace Mono.TextEditor
 		/// </summary>
 		public event EventHandler<EditModeChangedEventArgs> EditModeChanged;
 		
-		public TextEditor Parent {
+		public MonoTextEditor Parent {
 			get;
 			set;
 		}
@@ -207,24 +207,28 @@ namespace Mono.TextEditor
 			caret.PositionChanged += CaretPositionChanged;
 
 			options = TextEditorOptions.DefaultOptions;
-			
 			document = doc;
+			AttachDocument ();
+			SearchEngine = new BasicSearchEngine ();
+
+			HeightTree = new HeightTree (this);
+			HeightTree.Rebuild ();
+			IndentationTracker = new DefaultIndentationTracker (document);
+		}
+
+		void AttachDocument ()
+		{
+			if (document == null)
+				return;
 			document.BeginUndo += OnBeginUndo;
 			document.EndUndo += OnEndUndo;
-
 			document.Undone += DocumentHandleUndone;
 			document.Redone += DocumentHandleRedone;
 			document.LineChanged += HandleDocLineChanged;
 			document.TextReplaced += HandleTextReplaced;
-
 			document.TextSet += HandleDocTextSet;
 			document.Folded += HandleTextEditorDataDocumentFolded;
 			document.FoldTreeUpdated += HandleFoldTreeUpdated;
-			SearchEngine = new BasicSearchEngine ();
-
-			HeightTree = new HeightTree (this);
-			HeightTree.Rebuild ();
-			IndentationTracker = new DefaultIndentationTracker (document);
 		}
 
 		void HandleFoldTreeUpdated (object sender, EventArgs e)
@@ -267,6 +271,12 @@ namespace Mono.TextEditor
 			get {
 				return document;
 			}
+			set {
+				DetachDocument ();
+				document = value;
+				this.caret.SetDocument (document);
+				AttachDocument ();
+			}
 		}
 
 		void HandleTextReplaced (object sender, DocumentChangeEventArgs e)
@@ -805,6 +815,26 @@ namespace Mono.TextEditor
 			}
 		}
 
+		public int SelectionLead {
+			get {
+				if (MainSelection.IsEmpty)
+					return -1;
+				return MainSelection.GetLeadOffset (this);
+			}
+			set {
+				DocumentLocation location = Document.OffsetToLocation (value);
+				if (mainSelection.IsEmpty) {
+					MainSelection = new Selection (location, location);
+				} else {
+					if (MainSelection.Anchor == location) {
+						MainSelection = MainSelection.WithAnchor (MainSelection.Lead);
+					} else {
+						MainSelection = MainSelection.WithLead (location);
+					}
+				}
+			}
+		}
+
 		/// <summary>
 		/// Gets or sets the selection range. If nothing is selected (Caret.Offset, 0) is returned.
 		/// </summary>
@@ -888,6 +918,10 @@ namespace Mono.TextEditor
 		
 		public void SetSelection (int anchorOffset, int leadOffset)
 		{
+			if (anchorOffset == leadOffset) {
+				MainSelection = Selection.Empty;
+				return;
+			}
 			var anchor = document.OffsetToLocation (anchorOffset);
 			var lead = document.OffsetToLocation (leadOffset);
 			MainSelection = new Selection (anchor, lead);
@@ -895,7 +929,7 @@ namespace Mono.TextEditor
 
 		public void SetSelection (DocumentLocation anchor, DocumentLocation lead)
 		{
-			MainSelection = new Selection (anchor, lead);
+			MainSelection = anchor == lead ? Selection.Empty : new Selection (anchor, lead);
 		}
 
 		public void SetSelection (int anchorLine, int anchorColumn, int leadLine, int leadColumn)