I've got the same problem, it seems to happen if you right click before the tooltip appears. If you hover, wait for the tooltip, then right click everything works as expected.

I can't reproduce this, and opening the context menu should actually hide the tooltip regardless. Could either of you please record a video? That might give me a clue.

http://youtu.be/T53tqM2KIvQ
I would guess this has something to do with the Qt bug that causes the panel to freeze until you click on it again.

compared to kde4, menus don't seem to be modal anymore, so it's possible to open tooltips while menus are open (while it shouldn't be possible at all) even tough we seen that making them fully blocking brings other kinds of problems

one quite "interesting" thing is that some of the menus, like the containment one, exec() is called, but yet it doesn't block the gui. probably due to the aggressive multithreading occurring there

any way to see what's being done wrong at windows level?

in general, context menus in qt5 apps (tried with qt5 dolphin) seems to be "less modal" clicks elsewhere still dismiss the click but *do* pass the click, unlike qt4 apps,
I guess it's the usual qt xcb bug of the actual window flags only being applied a moment after being mapped

*** Bug 343463 has been marked as a duplicate of this bug. ***

It seems this problem does not exist any more.