Comment # 3 on bug 981358 from Egbert Eich

(In reply to Robby Engelmann from comment #2)
> I do not think that flickering in menus only sometimes is the same like
> flickering throughout the whole desktop everytime. I would guess that this
> time the xcb-update in the not yet released 20160523 is to blame.
> On my system all other "flickering" was resolved since 20160520 with 4.6
> kernel from Kernel:stable repo.

I personally don't expect libxcb to cause flickering. Of course I have not seen
what you call flickering. 
Right now, we have nothing to go by but your claim that it is libxcb that
caused it: To verify, did you try to downgrade to libxcb-1.11.1?