Trisquel 7 RC: Resizing windows in GNOME stops, continues

When I resize a window in GNOME the window often stops resizing just as
I begin the resizing mouse drag then, if I keep resizing, the resizing
continues normally.

I've never seen this behavior with any GNU/Linux or with X before, so I
thought I'd ask about it and see if this is particular to Trisquel or
this particular release candidate? Perhaps something else is involved I
don't know about?

Thanks.