There seems to be a conflict when using the Sitepress Multilingual CMS Plugin at the same time. The WPML debug mode outputs following error message:
Object of class WP_Error could not be converted to string (4096)
If I delete the line from the file the error obviously goes away and the cursor style changes but the Menubar Plugin seems to work just fine otherwise.
Anyway just wanted to let you know as I didn't find a way to fix this myself.