When I hover the mouse on the timeline looking for a specific time to click the popup bubble is hidden behind the Taskbar:

This does not happen with other apps (e.g. Audacity) -- when a bubble would normally appear out-of-frame it is forced to be inside the app's frame (though the result is sometimes strained/strange <grin>).
Wait--now I see the problem, when I click Maximize the MM window ends up too big--the bottom of the app's frame is hidden by the Taskbar. I think that is the real issue (although Audacity still gets the bubble in front of the Taskbar when Maximized would cause it to be in the Taskbar).
I'm not even sure how it got Maximized, I never did it intentionally--I always keep it as a non-Maximized window which is 99% full screen.

