Sorry that it is so much duplicate code now, but I decided that it is the easiest way for me to support both versions above and below gnome 40 by simply checking the version with if / else. I hope this is ok. Then I can remove the obsolete code very easy once the majority of users is on 40. Thank you for reviewing this and also for the new documentation on gjs and the porting guide. This helped me very much. I will also think about moving the ui stuff to a layout file like discribed there, should things make easier for me too in the future.

np. Also added Checking GTK Version to the port guide. You may like to use that: https://gjs.guide/extensions/upgrading/gnome-shell-40.html#checking-gtk-version