non-GL widgets appear black in windows containing a GtkGLArea
In gtk 3.22.30-1 running on 18.1.5 and X11, all non-GL appear black in windows containig a GLArea on certain drivers. Since I thought this to be a mesa bug, I filed a bug report with them: https://bugs.freedesktop.org/show_bug.cgi?id=107530#c6 Turns out, gtk might be doing the wrong thing
GTK+ tries to be clever by reading back it's front buffer into the back buffer. What I found is that DRI3 will outright prevent you from reading back the front buffer of a window
Maybe someone familiar with gtk's opengl machinery can comment on this?