Once the klipper menu is open, there seems to be no way to dismiss it without choosing a menu entry Reproducible: Always
Other thing is, this menu overlaps the panel icon. so one can not click on the system tray icon.. and losing focus does not close the menu.
*** Bug 333278 has been marked as a duplicate of this bug. ***
*** This bug has been marked as a duplicate of bug 335015 ***
Reopening this one as I can't reopen the duplicate one. This still happens if you quit and restart plasmashell inside the plasma session.
This does not apply anymore to the new QML klipper