{
    // Remove any menu items for old selection.
    //
    if (createChildMenuManager != null)
    {
      depopulateManager(createChildMenuManager, createChildActions);
    }
    if (createSiblingMenuManager != null)
    {
      depopulateManager(createSiblingMenuManager, createSiblingActions);
    }

    // Query the new selection for appropriate new child/sibling descriptors
    //
    Collection<?> newChildDescriptors = null;
    Collection<?> newSiblingDescriptors = null;

    ISelection selection = event.getSelection();
    if (selection instanceof IStructuredSelection && ((IStructuredSelection)selection).size() == 1)
    {
      Object object = ((IStructuredSelection)selection).getFirstElement();

      EditingDomain domain = ((IEditingDomainProvider)activeEditorPart).getEditingDomain();

      newChildDescriptors = domain.getNewChildDescriptors(object, null);
      newSiblingDescriptors = domain.getNewChildDescriptors(null, object);
    }

    // Generate actions for selection; populate and redraw the menus.
    //
    createChildActions = generateCreateChildActions(newChildDescriptors, selection);
    createSiblingActions = generateCreateSiblingActions(newSiblingDescriptors, selection);

    if (createChildMenuManager != null)
    {
      populateManager(createChildMenuManager, createChildActions, null);
      createChildMenuManager.update(true);
    }
    if (createSiblingMenuManager != null)
    {
      populateManager(createSiblingMenuManager, createSiblingActions, null);
      createSiblingMenuManager.update(true);
    }
  }