private void OnKeyDown(object sender, KeyEventArgs e)
 {
     if (e.Key == Key.Delete)
     {
         OutlinerItemModel sObjModel = outlinerTreeView.SelectedItem as OutlinerItemModel;
         mainWindow.RemovePropertiesPanel();
         IGCore.DeleteSceneObject(sObjModel.Name);
         Refresh();
     }
 }