Sometimes a badly configured tablet can generate X errors on the XOpenDevice method. Fixed by ensuring tablet driver was functional. I don't know if the errors need to be caught, or not, but I think they were causing crashes. This is probably related to synchonous/asynchonous X modes.
In case you want to catch this, there is a mechanism in place in Wine to handle X calls which can lead, in 'normal usage' to X11 error being sent.
Look at, for example, the DGA2 initialization.
Lionel