This is a continuation of #657172 but I've been told not to post to closed bugs. The WONTFIX resolution was a poor decision IMO, because the proposed workaround described at < http://who-t.blogspot.com/2011/03/custom-input-device-configuration-in.html> turns out not to work correctly.

If I return 0 from my script this prevents g-s-d from applying its other settings so I lose edge scrolling etc. If I return 1 g-s-d overwrites the setting I've just applied in the script. OK, I can return 1 while starting a background subshell to apply my setting after a short sleep, but that's an ugly kludge, prone to race conditions. And I presume if I changed a related option in the capplet I'd have to reapply my setting afterwards.

The only elegant way to fix this is to provide an option in g-s-d and the capplet. I can't see a justification not to provide this option when you do provide an option to swap left and right buttons. I can't see any use for that except as a prank. I'm left-handed myself and have never wanted to use that option on ordinary mice or touchpads.