http://bugs.winehq.org/show_bug.cgi?id=6971
This bug can only be resolved if Wine uses XI2. But work on this does not get accepted because then this bug wouldn't be fixed if Wine were to run on older X.org versions (*sigh*). However other fixes are not welcomed because according to the people in charge Wine shall only use a clean XI2 implementation instead of ugly hacks. >.<
Well, a simple fix would be to add conditional X Input 2 support into Wine which won't be used unless people have new enough X.org, wait until most people migrate to X.org with X Input 2 support, make Wine require the version of X.org, and then close the bug.