To reproduce: - open a menu from a systray icon, which provides one (left, right click does not matter) - open a menu item or just click outside the panel to collapse the menu - panel stays unhidden, until one moves the mouse pointer again over the panel Seems like there is some sort of deactivation signal missing, when the menu collapses.
This one has already been reported and is probably unfixable :/ *** This bug has been marked as a duplicate of bug 11509 ***