Multi Pointer X (MPX) support
I'm wondering how multiple pointers should/could be handled by a high level application.
I'm mostly interested about how MPX (Multi Pointer X - for Xorg) works. What GUI libraries support it?
It seems like latest versions of Qt and GTK should support it, but cannot find any demo, tutorial or documentation.
Experimental support for MPX in GTK+ can be found here. Since that's a work in progress, documentation is very scarce but still might get you started.
There's documentation about MPX itself here.
Note that existing applications using only one pointer will be able to run unchanged on an MPX-aware server. If you want your app to take advantage of multiple pointers, you'll need to call gdk_enable_multidevice() before gtk_init() and handle per-device enter/leave events and grabs.