Comment # 3 on bug 1000538 from Mindaugas Baranauskas

No, this is not duplicate, because boo#1000514 don't appears after re-login (as
bug#1000510 also); while boo#1000538 I observed in later times of login. Note:
I observe this bug not consistently; and higher rate seems to be after creating
new panel at top edge and removing it. I just guess: notification widget in
second panel sometimes was not immediatly removed?... 
But maybe, yes (I don't know), we can suspect, that underlaying mechanism may
be related with all three mentioned bugs...