Hi,

I'm not sure this is the right package to file a bug against, so please
reassign if needed.

A recent update to something in the X stack causes random font
corruptions. Some of the characters display as blocks or random noise,
or change over time (first render normally, but after a window refresh
display incorrectly). I have also noticed window manager decorations
are sometimes corrupted too.

Hello,

And now this (see the attachment).

Dear Maintainer,

   * What led up to the situation?

upgrading from Jessie to Stretch + reboot/restart of X

Shown application windows are randomly garbled but are properly redrawn
if mouse is moved over garbled areas and/or windows are resized.

Please have a look at the attachment where garbled sections can be seen
at the top and lower left corner of icedove.

I hope this helps a bit identifying the issue.

Cheers

Carsten