All KDE software built from today's git master on top of openSUSE Tumbleweed
I've set my cursor size to 48px, and this size is displayed when the cursor is over a KDE app, a part of Plasma, or a KWin-drawn window decoration. However when the cursor is over a GTK app, it reverts to its default 24px size
Sounds to me like a GTK bug. The client must set the cursor image when the pointer enters one of its surfaces.
CCing some of our people with GTK expertise.
Note that xcursor_size is an environment variable (which sucks) so you need to log out and back in again to see changes.
Edit, just reproduced after logging out and in with the env set.
In any case, this still remains a GTK bug and a report should be filed there, closing this as upstream afterwards.
Reading GTK code they do follow gtk-cursor-theme-size
We could get our gtk-config bridge to sync it just like we sync the theme.
Doesn't really fix the root problem of not having a global spec, but it'd hide the symptoms.
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kde-gtk-config/-/merge_requests/8
Git commit 8359e316e7b14e81f4cbdf4ceb14783b7c90fc44 by Mikhail Zolotukhin.
Committed on 17/07/2020 at 13:39.
Pushed by gikari into branch 'master'.
Synchronize the cursor size setting
M +1 -1 README.md
M +6 -0 kded/configvalueprovider.cpp
M +1 -0 kded/configvalueprovider.h
M +17 -3 kded/gtkconfig.cpp
M +1 -0 kded/gtkconfig.h