The other day an X.org developer asked me if Wine needed anything from X. Off the top of my head, all I could think to tell him was relative mouse movements.
Input isn't really my area but I believe we need relative mouse movements for the whole desktop and not for a single window. Ask vitaly for more info on what is needed. Input is the biggest issue in most recent games on Wine (Unreal Tournament III, Crysis and dozens of others)
Roderick