[Users] how to darken Claws-mail windows?

[Pierre A.]

> That's controlled by your gtk theme. 

Finally I found something that had some effect:

https://extensions.gnome.org/extension/4968/lightdark-theme-switcher/

However, the dark version is hardly readable because every other one mailbox has white letters on whitish background.  (If useful and possible I will send a screenshot.)

Just having white on black (like Gnome terminal) instead of black on white would be enough for me.