I just had an opportunity to do a fresh bookworm install and encountered the
same problem. I was able to fix it with the following steps.
1. Change the main theme from Breeze Dark to Breeze.
2. Change the cursor theme from Breeze to Breeze Light.
At this point, I rebooted for other reasons. That probably isn’t needed, but
I mention it just in case.
I then opened a GTK app an noticed that the cursor was displaying dark just
inside the app.
3. Change the cursor theme from Breeze Light to Breeze.
4. Change the cursor theme from Breeze back to Breeze Light.
This resolved the problem on bookworm for any GTK app opened after completing
step 4. Sid might be a little different.
--
Soren Stoutner
so...@stoutner.com