Yup, and it's quite non-trivial. The typical GTK application out there can't handle multi-touch and can rarely even handle several mouse events (e.g.: mouse-wh

Yup, and it's quite non-trivial. The typical GTK application out there can't handle multi-touch and can rarely even handle several mouse events (e.g.: mouse-wheel scroll while dragging), so I doubt they have full blow support for multiple seats.