HiDPI support is broken

Hi all

I am surprised that HiDPI scaling is broken in Mate 1.26.

Steps to reproduce:

  1. Mate Tweak > Windows > HiDPI change from "auto" to "HiDPI"
  2. Result: A lot of flickering then everything looks fine at 200%
  3. Reboot & login: Window title buttons are all of a sudden unscaled again while the rest is as expected (see image)
  4. Default wallpaper is grainy at 200% // No workaround
  5. Workaround: Mate Tweak > Windows > HiDPI change from "HiDPI" to "auto" and back to "HiDPI"

Is this a known issue and are there any ways to remedy this?

I found another workaround to restore the expected window button size. Change theme from Yaru Light to something else and back to Yaru light.

I wonder if the theme is broken or this is an issue with the window manager.