When using mouseconfig-4.15.2-1 and checking the Emulate three button box it always writes XEMU3=yes to /etc/sysconfig/mouse despite unchecking the box.
This defect is considered MUST-FIX for Florence Gold release
According to the code, this behavior is intentional.
This looks like it's fixed in mouseconfig-4.16-1. I tried enabling the emulate 3 button option, it worked properly, unchecking it works properly as well. I am resolving this as "rawhide". Tim