code: @Override
  	public void renderHead(IHeaderResponse response) {
  		super.renderHead(response);
  
  		response.render(JavaScriptHeaderItem.forReference(DRAWER_JAVASCRIPT));
  		response.render(JavaScriptHeaderItem.forReference(MANAGER_JAVASCRIPT));
  		response.render(CssHeaderItem.forReference(DRAWER_CSS));
  
  		Iterator<ListItem> iter = drawers.descendingIterator();
  		WebMarkupContainer drawer;
  		while (iter.hasNext()) {
  			drawer=iter.next().item;
  			response.render(OnDomReadyHeaderItem.forScript("$('#"+drawer.getMarkupId()+"').modaldrawer('show');"));
  			if (drawers.getFirst().item.equals(drawer)) {
  				response.render(OnDomReadyHeaderItem.forScript("$('#"+drawer.getMarkupId()+"').addClass('shown-modal');"));
  				response.render(OnDomReadyHeaderItem.forScript("$('#"+drawer.getMarkupId()+"').removeClass('hidden-modal');"));
  			} else {
  				response.render(OnDomReadyHeaderItem.forScript("$('#"+drawer.getMarkupId()+"').removeClass('shown-modal');"));
  				response.render(OnDomReadyHeaderItem.forScript("$('#"+drawer.getMarkupId()+"').addClass('hidden-modal');"));
  			}
  		}
  	}
docs: pressing the Back button and landing on a page with open drawers.