code: protected void renderSelectTag(FacesContext context, ResponseWriter rw, String clientId, String name,
  			SelectMultiMenu menu) throws IOException {
  		renderSelectTag(rw, menu);
  		renderSelectTagAttributes(rw, clientId, name, menu);
          AJAXRenderer.generateBootsFacesAJAXAndJavaScript(FacesContext.getCurrentInstance(), menu, rw, false);
  		Object selectedOption = getValue2Render(context, menu);
  		String[] optionList;
  		if (selectedOption == null) {
  			optionList = new String[0];
  		} else if (!(selectedOption instanceof String)) {
  			throw new FacesException("SelectMultiMenu only works with Strings!");
  		} else {
  			optionList = ((String) selectedOption).split(",");
  		}
  		renderOptions(context, rw, optionList, menu);
  
  		renderInputTagEnd(rw);
  	}
docs: Renders the select tag.