public void Execute(SharpTreeNode[] selectedNodes)
        {
            var typeDefinition = selectedNodes
                .OfType<TypeTreeNode>()
                .Single().TypeDefinition;

            var window = new AncestryBrowserWindow(typeDefinition)
                         	{
                         		Owner = MainWindow.Instance
                         	};
            window.Show();
        }
 private void BrowseAncestryCommandHandler()
 {
     var window = new AncestryBrowserWindow(_typeDefinition)
     {
         Owner = MainWindow.Instance
     };
     window.Show();
 }