GTK+ window position

[Bob <4bob+go mailbox org>]

Distribution: Ubuntu 20.04
Desktop Environment: Budgie/Gnome
Backend: X11

Hello,

I have a problem with GTK+ Applications. (like GParted, cherrytree... )
Additional Windows like popups, info screens etc. are displayed fixed in
the middle of the application.
Its not possible to move them. What is the best way to reset GTK+ 3
settings?
dconf reset -f /org/gtk/ don't work or it‘s something else.
This is it how it looks like:
https://s12.directupload.net/images/201008/4hlxwmik.gif

In the meantime, thank you so much for your attention and participation.
Kind regards
Bob