Help/Feedback on MR for a Keyboard Shortcut Fix in libxfce4ui

Hello,

I've created a draft merge request for libxfce4ui to allow keyboard
shortcuts consisting of only modifier keys (say, Super_L to open an
application menu) to work properly without interfering with others that
use these keys. It partially works, however I have a few areas in which
I need feedback/advice, mainly in getting it to work with xfwm4. Could
someone familiar with xfwm4/libxfce4ui take a look at it? 

Here is a link to the merge request in question:
https://gitlab.xfce.org/xfce/libxfce4ui/-/merge_requests/102

Thank you for taking the time to read this!

Sincerely,
Elliot