Remove DocumentContent from DocumentPane when workbench window is closed.

git-svn-id: svn://svn.sharpdevelop.net/sharpdevelop/branches/3.0wpf@3369 1ccf3a8d-04fe-1044-b7c0-cef0b8235c61

src/Main/Base/Project/Src/Gui/Pads/PropertyPad/PropertyPad.cs

@@ -178,6 +178,7 @@ namespace ICSharpCode.SharpDevelop.Gui
 			
 			panel.Controls.Add(grid);
 			panel.Controls.Add(comboBox);
+			contentControl.SetContent(panel);
 			
 			ProjectService.SolutionClosed += SolutionClosedEvent;
 			

src/Main/Base/Project/Src/Gui/Workbench/Layouts/AvalonWorkbenchWindow.cs

@@ -340,6 +340,7 @@ namespace ICSharpCode.SharpDevelop.Gui
 				}
 			}
 
+			dockLayout.DocumentPane.Items.Remove(this);
 			Dispose();
 			return true;
 		}