re-write using Cocoa
Gnome Super shortcuts circumvent the NSScreenSaverWindowLevel flag in Cocoa.
To disable use gnome-tweaks->keyboard and mouse. Switch from left super to right super
or
gsettings set org.gnome.mutter overlay-key ""
@see https://askubuntu.com/questions/93746/how-can-i-disable-the-windows-key-from-opening-the-activities-overview