Fix the ungrab label sometimes rendering wrong
Fix the ungrab label sometimes rendering wrong

The Spice widget is sometimes sending mouse grab changed signals
while inside gtk_widget_size_allocate() which means any size
alllocation changes we request are ignored. This caused the
label rendering issue.

We work around this by delaying the change to an idle.

https://bugzilla.gnome.org/show_bug.cgi?id=692465

vbenes/gnome-boxes,vbenes/gnome-boxes