ActionBarSherlock: open submenu with menu button
===

I'm using ActionBarSherlock-4.1.0-0 and I would like to open my submenu in the Actionbar with the hardware menu button. I'm planing an update and in my old version I used the "normal" menu. I'd like to help users to get used to the new design.
I got the submenu and the main-menu:

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		MenuInflater i = getSupportMenuInflater();
		i.inflate(R.menu.main_menu, menu);
		SubMenu subMenu = (SubMenu) menu.findItem(R.id.actionbar_submenu);
        Menu mainMenu = menu;
		return super.onCreateOptionsMenu(menu);
	}


and i got a listner to the hardware menu button:

	@Override
	public boolean onKeyDown(int keyCode, KeyEvent event) {
		if(event.getAction() == KeyEvent.ACTION_DOWN){
			switch(keyCode) {
			case KeyEvent.KEYCODE_MENU:
				// TODO: expand submenu from actionbar
				return true;

			}
		}
		return super.onKeyDown(keyCode, event);
	}

I couldn't find a method or anything else to call. I hope you can help me,
cheers,
Paul