Graphics glitches in Firefox window
Frequently, when I am surfing the web, graphical glitches appear in the Firefox window. Generally the glitches disappear on the next redraw. Here's a screenshot of the issue: https://bug1440975.bmoattachments.org/attachment.cgi?id=8953804
I have no idea if this is a bug in Firefox, my desktop's compositor (Gnome), the Intel graphics driver or the nouveau graphics driver (both of which are involved because this is on a screen connected to a PRIME output slave). However, I have not (yet) seen this issue in any other application.
I first reported this against Firefox at https://bugzilla.mozilla.org/show_bug.cgi?id=1440975, but was advised that the glitches look like they are introduced by the compositor.
This is on Debian testing with gnome-shell 3.26.2-4 and libmutter 3.26.2-1.