public ModelElementsPropertiesPanel() {
   setLayout(new BorderLayout(GUI.HorizontalWidgetDistance, 0));
   setBorder(GUI.getEmptyPanelBorder());
   toolbar = createToolbar();
   if (toolbar != null) {
     add(toolbar, BorderLayout.NORTH);
   }
   Component details = createDetailsPanel();
   if (details != null) {
     add(details);
   }
   Component list = createListPanel();
   if (list != null) {
     add(list, BorderLayout.WEST);
   }
 }