Created attachment 342773 [details]
Issue

This bug is a bit tricky to reproduce :

- you need to run under a wayland compositor.
- you need to have a primary screen at scaling factor of 2 and secondary screen of scaling factor 1

If you open devhelp on the secondary screen, the scaling factor is right in the first tab. But if you open another tab, the scaling factor will be the one of the primary screen.

This will be fixed if you move the devhelp window from the secondary to primary screen and back.

Attached is a video of issue, I could only record the problem in a nested compositor (because video encoder limitations with regards of the texture size).
You can have the same setup by launching mutter with :

MUTTER_DEBUG_NUM_DUMMY_MONITORS=2 MUTTER_DEBUG_DUMMY_MONITOR_SCALES=2,1 mutter --wayland --nested

And devhelp with :

WAYLAND_DISPLAY=wayland-1 devhelp