Merge pull request #2615 from cwensley/curtis/treegridview-collapse-o…

…nly-when-not-editing

Wpf: Only expand/collapse/go to parent on left key when not editing

src/Eto.Wpf/Forms/Controls/TreeGridViewHandler.cs

@@ -22,7 +22,7 @@ protected override void Initialize()
 
 		private void Control_PreviewKeyDown(object sender, sw.Input.KeyEventArgs e)
 		{
-			if (e.Handled || swi.Keyboard.Modifiers != swi.ModifierKeys.None)
+			if (e.Handled || swi.Keyboard.Modifiers != swi.ModifierKeys.None || IsEditing)
 				return;
 
 			// handle expanding/collapsing via the keyboard