fix #538: WPF Commands do not work properly in Windows Forms ContextMenus

Author: siegfriedpammer

src/Main/ICSharpCode.Core.WinForms/Menu/MenuCommand.cs

@@ -100,7 +100,8 @@ public virtual void UpdateStatus()
 					} catch (ResourceNotFoundException) {}
 				}
 				Visible = GetVisible();
-				Enabled = command != null && command.CanExecute(caller);
+				command = CommandWrapper.Unwrap(command);
+				Enabled = command != null && MenuService.CanExecuteCommand(command, caller);
 			}
 		}
 

src/Main/ICSharpCode.Core.WinForms/Menu/MenuService.cs

@@ -28,6 +28,7 @@ namespace ICSharpCode.Core.WinForms
 	public static class MenuService
 	{
 		public static Action<System.Windows.Input.ICommand, object> ExecuteCommand;
+		public static Func<System.Windows.Input.ICommand, object, bool> CanExecuteCommand;
 
 		public static void AddItemsToMenu(ToolStripItemCollection collection, object owner, string addInTreePath)
 		{

src/Main/SharpDevelop/Workbench/WpfWorkbench.cs

@@ -137,6 +137,7 @@ public void Initialize()
 			dockPanel.Children.Insert(dockPanel.Children.Count - 2, statusBar);
 
 			Core.WinForms.MenuService.ExecuteCommand = ExecuteCommand;
+			Core.WinForms.MenuService.CanExecuteCommand = CanExecuteCommand;
 			UpdateMenu();
 
 			AddHandler(Hyperlink.RequestNavigateEvent, new RequestNavigateEventHandler(OnRequestNavigate));
@@ -160,9 +161,9 @@ void ExecuteCommand(ICommand command, object caller)
 		{
 			ServiceSingleton.GetRequiredService<IAnalyticsMonitor>()
 				.TrackFeature(command.GetType().FullName, "Menu");
-			var routedCommand = command as System.Windows.Input.RoutedCommand;
+			var routedCommand = command as RoutedCommand;
 			if (routedCommand != null) {
-				var target = System.Windows.Input.FocusManager.GetFocusedElement(this);
+				var target = FocusManager.GetFocusedElement(this);
 				if (routedCommand.CanExecute(caller, target))
 					routedCommand.Execute(caller, target);
 			} else {
@@ -171,6 +172,17 @@ void ExecuteCommand(ICommand command, object caller)
 			}
 		}
 
+		bool CanExecuteCommand(ICommand command, object caller)
+		{
+			var routedCommand = command as RoutedCommand;
+			if (routedCommand != null) {
+				var target = FocusManager.GetFocusedElement(this);
+				return routedCommand.CanExecute(caller, target);
+			} else {
+				return command.CanExecute(caller);
+			}
+		}
+		
 		// keep a reference to the event handler to prevent it from being garbage collected
 		// (CommandManager.RequerySuggested only keeps weak references to the event handlers)
 		EventHandler requerySuggestedEventHandler;