Just came across this odd bug following an update to KDE Frameworks following a zypper dup of my TW machines.
Open a GTK application, Firefox for example, and click on a dropdown or foldout or open a context menu by right clicking and the cursor changes from the currently set theme, (Breeze, Oxygen, whatever), to Adwaita. Click again elsewhere and the cursor reverts to the themed one.
Found this upstream bug report: https://bugs.kde.org/show_bug.cgi?id=459670 (as yet not responded to), which indicates it may be fallout from a fix introduced for a problem on wayland. I will follow it with interest…
Courtesy of @jamesxmcintosh over on the KDE bugzilla.
There is a workaround for this issue, see: https://bugs.kde.org/show_bug.cgi?id=459670#c2
That successfully worked on my systems, tested with FF, TB, and Gimp. (You would need to change the “Oxygen_White” to match your cursor theme, and probably make a note, mental or otherwise, of the change made).
I went looking for this but and for me it does not change anything permanently. If I click on a menu item in FF yes it changes but as soon as I move back to the body it goes back to my setting. I use Oxygen Blue for my cursor/pointer if that makes a difference.
Perhaps my description in the initial post was a little vague, it’s not, as you say, a permanent change. The cursor was changing back and forth between the set theme and Adwaita depending upon where or what action the cursor was indicating. I also found that if you simply hovered and moved left/right over items on the bookmarks toolbar sometimes the cursor would change and sometimes not.
The bug didn’t prevent normal use of GTK applications, but I personally found it very visually irritating, I guess that’s the grumpy old man syndrome kicking in …
My wife thinks I’ve been one for some years now I must admit I only noticed when I went looking for it after seeing the original post.