Menu items without link

I’ve managed to do this by adding the following code to the responsive-select-menu.php file.

Find the following code (probably line 587-589)

if( $responsiveMenuSelect->getSettings()->op( 'current_selected' ) && strpos( $class_names , 'current-menu-item' ) > 0 ){
			$attributes.= ' selected="selected"';
		}

and the code below right after:

if( ( $item->url == '#' || $item->url == '' ) ){
			$attributes.= ' disabled';
		}

Now the items without link are greyed out. You should have set the option “Exclude items without links” to “off”.