(In reply to Diego Viola from comment #24)
> I've bisected the issue with the GTK elements sometimes disappearing, and
> the commit that causes the issue is this one:
> 
> 1b25d340b791ad8350bdfb27f1a91ac79fa17748 is the first bad commit

Can you double-check this with Xephyr, taking everything we've learned since
then into account, and if the same commit is identified again, file a new
report about it?