Comment # 8 on bug 1026999 from Axel Schwank

PS. If you open a context menu with right-click from the systray icon and do
not activate anything from it but just click somewhere else, sometimes the menu
closes but sometimes it stays. I was not able to find out what triggers the
different behaviour.

If it does not close, you have to close it manually from the window list.
While this is not quite the old behaviour from KDE4, I think, I still would
suggest to ignore this and submit anyway as this is really minor from my point
of view. The fix is a huge improvement.