I’m happy that you like the app. GfxTablet pressure sensitivity is handled by the MotionEvent API automatically. I think if there’s no hardware support for pressure, the API tries to emulate it – so the pressure info should be available to all apps, no only GfxTablet.
Yep the reserve for pressure makes sense, but the coordinates are also interpreted as having a max value of 32768, not 65536. This is because the server code interprets these values as signed shorts, not unsigned shorts, and uses SHRT_MAX as the maximum to normalize with, not USHRT_MAX.
Indeed, it should interpret the values as an unsigned short and normalize to USHRT_MAX/2.