Comment 18 for bug 1024482

While mucking around in gtk/gdk, I discovered a better workaround for
this bug. While logged in as some user with sudo access, run the commands:

echo "GDK_CORE_DEVICE_EVENTS=true" | sudo tee ~lightdm/.pam_environment
sudo chown lightdm:lightdm ~lightdm/.pam_environment

This ensures that the next time any one of the lightdm greeters are run,
it will have an environment variable named GDK_CORE_DEVICE_EVENTS set.
This in turn causes gdk to disable its use of XInput2, thus avoiding
this bug. Once those commands are run, xsetroot and friends should work
upon the next login.

HTH!