One of the annoying problems when controlling an HTPC is a periodic need to use the mouse/keyboard to do certain operations that otherwise are either not convenient or simply impossible to do with a remote.

Having a mouse/keyboard in the media room just for that purpose works, but it sure would be great if the remote controller could also cover some of those needs.

The current Pronto Professional lineup can easily be configured to be used as a virtual keyboard via IR. Going serial for that purpose also is trivial. A little more involved, but doable, is implementing this functionality using TCP/IP.

But is it possible to use the touchscreen as a trackpad? Does the hardware allow low enough response time and high enough linear resolution for this (the software part is more or less understood - there is a widget.onMove callback now available and it's just a matter of implementing the corresponding driver and transport)?

Does anyone know if the relevant touchscreen HW specs are documented?

Thanks!

Depends on what you need in regards of the specs. The specs of the touch grid are not given as far as I know but you can test it. Make some movable widgets and calculate how the lowest distance you can move them, if I remember correctly you can move them by a couple of pixels (2-3) so the touch resolution is usable.

Everything else depends on the "driver" you write for the "pronto trackpad" you can incorporate acceleration and other stuff the usual laptop tack pads use to make them useful to move an arrow across the large screen in respect to the sie of the trackpad.

IP? Sure, if you have something on the HTPC side that can translate the incoming IP data as mouse movement.