I raised this issue sometime back but I can't find the thread, however I have more details on the issue.
If I have a dock that is not minimised to the tray, I can get LBC to show hints on items at the top level but not in lower menus. If I minimise the dock to the tray, then no hints show at all. I have attached a few screenshots to show what I mean (or at least what I am trying to convey). I also included a test dock (zipped as I couldn't upload it as it was an invalid extension) that I used for testing the problem.