Bug 157072 [ActionSets][Contributions] QuickMenuAction funtionality should be made public
The QuickMenuAction class should be made public and usable by IWorkbenchWindowPulldownDelegate{2}. As it is you need to roll this functionality yourself in the run method of your delegate (and it is by no means straightforward).
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/actions/QuickMenuAction.java
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Menu;
import org.eclipse.swt.widgets.Table;
import org.eclipse.swt.widgets.TableItem;
import org.eclipse.swt.widgets.Tree;
import org.eclipse.swt.widgets.TreeItem;
import org.eclipse.ui.IWorkbench;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.keys.IBindingService;
/**
 * A quick menu actions provides support to assign short cuts
 * to sub menus.
 * 
 * @since 3.0
 */
public abstract class QuickMenuAction extends Action {
    private static final int CHAR_INDENT = 3;
    private Menu quickMenu;
    /**
     * Creates a new quick menu action with the given command id.
     * 
     * @param commandId the command id of the short cut used to open
     *  the sub menu 
     */
    public QuickMenuAction(String commandId) {
        setId(commandId);
        setActionDefinitionId(commandId);
    }
    /**
     * {@inheritDoc}