Comment # 17 on bug 75128 from publicface@bak.rr.com

That particular window was just ONE example that happened to be available at
the time I was able to get the snapshot.  The fact of the matter is more than
one application leaves artifacts, not just google chrome.  One of those
screenshots clearly shows a dialpad - which comes from jitsi.

Therefore it is not likely to be an application issue, as at least two
applications leave artifacts as can be seen from the screenshot.