code: public void replaceLast(AbstractDrawer newDrawer, AjaxRequestTarget target) {
  		if (!drawers.isEmpty()) {
  			ListItem last = drawers.getFirst();
  			last.drawer.replaceWith(newDrawer);
  			last.drawer = newDrawer;
  			newDrawer.setManager(this);
  			target.add(newDrawer);
  		}
  	}
docs: Replaces the topmost open drawer with a new one. If there is no open drawer, this method does nothing.
  This method requires an AJAX request. DrawerManager does not support swapping drawers during page construction.
  
  @param newDrawer
  The new drawer to open. Cannot be null.
  @param target
  The current AJAX target. Cannot be null.