OS: Ubuntu Linux 22.04 LTS - 64bit, XFCE 4.18 (packages from xubuntu-dev ppa, ppa:xubuntu-dev/staging), Greybird gtk theme
After opening XnView there's a wrong background/color on some ui elements of program. E.g. unreadable tooltips, wrong background in places, etc.
Effect: Some ui elements appears incorrect after program has been launched. Quickly changing theme and returning to previous solves the problem until restart of application. Screenshots:
To reproduce:
1. (optionally) set another user, log in to it
2. Start XnView while using XFCE 4.18 environment, making sure QT_QPA_PLATFORMTHEME env. variable is set to gtk2 (xubuntu has it on /etc/X11/Xsession.d/56xubuntu-session), complete initial setup if prompted, make sure theme selected during setup is default
3. Observe incorrect appearance of the program, notice appearance returns to normal after changing theme and returning to the previous one.
Actual behaviour (bug): Incorrect gtk theme appearance
Expected behaviour: Gtk theme appearing correctly, no wrong backgrounds and/or colors in places.
Thanks to your detailed description I can reproduce