If the BoxPointer changes size (eg, when opening the "More" section of
the network menu), reposition it to make sure it's still aligned
correctly and still completely on-screen.
This is not the right fix for this problem (and causes the menu to be
drawn in the wrong position for one frame). The right fix would
involve a ClutterConstraint, but that would be more invasive, and can
happen post-3.0.0.
https://bugzilla.gnome.org/show_bug.cgi?id=645647
475161f716