I was the original writer of bug #873562 - my bug was marked as a duplicate of this bug.
BUT: it's not always the second monitor! I cannot tell you how it happens, but sometimes it affects my main monitor while my secondary monitor is keeping the menu!
So: this bug's description is not quite correct.
Please fix this - it is definitely a regression! 11.04 was not affected!
I was the original writer of bug #873562 - my bug was marked as a duplicate of this bug.
BUT: it's not always the second monitor! I cannot tell you how it happens, but sometimes it affects my main monitor while my secondary monitor is keeping the menu!
So: this bug's description is not quite correct.
Please fix this - it is definitely a regression! 11.04 was not affected!