Messenger, MSN Messenger at least, as i said before, things get loaded and destroyed, regurding menus, so maybe you could remove the unsertainty by catching the LoadMenuA api, which is sent before every TrackPo..., to see which resource gets loaded every time, and catch the menu handle, and build from thereon
But i guess you would figure this out, way before !!!
(it is just a suggestion, not that i had any problems so far with Plus menu addons...
)