I like the Kali-Dark theme, but I also like the "pin" and "shade" buttons in my windows.
Adding them I noticed, that the Kali-Dark theme didn't treat them consistent with the "hide" and "maximize" buttons.
So I fixed that.

However, once you have a slew of buttons up there, the completely blank buttons that one needs to mouse over to see what they are doing, didn't make sense anymore. The result looks like this (active and inactive window (with all buttons shown, which is of course a separate configuration step)):

Screenshot 2022-05-10 15:00:26.png

The modified folder from /usr/share/themes/Kali-Dark/xfwm4/ is included as a zip file, for anyone who wants to use the fix (or include in an update...)
What would remain to do, is to do the equivalent changes for the Kali-Dark-xHiDPI, Kali-Light, and Kali-Light-xHiDPI themes.

Hope that's useful...xfwm4.zip