Attempt to fix an exception that sometimes occurs when closing the workbench while an open text editor view has a selection.

git-svn-id: svn://svn.sharpdevelop.net/sharpdevelop/branches/3.0@3547 1ccf3a8d-04fe-1044-b7c0-cef0b8235c61

src/Main/Base/Project/Src/TextEditor/Gui/Editor/TextEditorDisplayBinding.cs

@@ -451,31 +451,31 @@ namespace ICSharpCode.SharpDevelop.DefaultEditor.Gui.Editor
 		#region ICSharpCode.SharpDevelop.Gui.IClipboardHandler interface implementation
 		public bool EnableCut {
 			get {
-				return textEditorControl.ActiveTextAreaControl.TextArea.ClipboardHandler.EnableCut;
+				return !this.IsDisposed && textEditorControl.ActiveTextAreaControl.TextArea.ClipboardHandler.EnableCut;
 			}
 		}
 		
 		public bool EnableCopy {
 			get {
-				return textEditorControl.ActiveTextAreaControl.TextArea.ClipboardHandler.EnableCopy;
+				return !this.IsDisposed && textEditorControl.ActiveTextAreaControl.TextArea.ClipboardHandler.EnableCopy;
 			}
 		}
 		
 		public bool EnablePaste {
 			get {
-				return textEditorControl.ActiveTextAreaControl.TextArea.ClipboardHandler.EnablePaste;
+				return !this.IsDisposed && textEditorControl.ActiveTextAreaControl.TextArea.ClipboardHandler.EnablePaste;
 			}
 		}
 		
 		public bool EnableDelete {
 			get {
-				return textEditorControl.ActiveTextAreaControl.TextArea.ClipboardHandler.EnableDelete;
+				return !this.IsDisposed && textEditorControl.ActiveTextAreaControl.TextArea.ClipboardHandler.EnableDelete;
 			}
 		}
 		
 		public bool EnableSelectAll {
 			get {
-				return textEditorControl.ActiveTextAreaControl.TextArea.ClipboardHandler.EnableSelectAll;
+				return !this.IsDisposed && textEditorControl.ActiveTextAreaControl.TextArea.ClipboardHandler.EnableSelectAll;
 			}
 		}