If you have problems with mouse pointer size in Flatpak on HiDPI...

Do you have problems with mouse pointer size in Flatpak on HiDPI? Hey, everyone does!

This sounds like a very specific problem, but people complain a lot, especially since it affects such applications as Discord and Spotify. So, here is the solution. Well, the real solution is to make the package maintainers to fix their stuff, but c'mon, we all know that they will not.

So, the next best thing would be to force the mouse pointer shape and size onto an application. The trick is that the theme name must be precise and the size must be one of the sizes supported by the pointer theme. Otherwise it will revert to defaults.

For example, lets fix Spotify.

sudo flatpak override --env=XCURSOR_THEME=Adwaita com.spotify.Client sudo flatpak override --env=XCURSOR_SIZE=72 com.spotify.Client 

Tada! The pointer should be conveniently engorged. By the way, if you find the font in Spotify client too small, just add --force-device-scale-factor=3 argument to the command line.