This question is a bit hard to put in the right forum, as there is no generic Maemo support forum yet, but the question is Qt-related, so here it goes.

The Maemo 5 powered N900 has a resistive touch screen and can therefore not support multi-touch. Qt is now available for Maemo, but without multi-touch support either (AFAIK). Qt will support multi-touch in Qt 4.6. My question is about backwards-compatability. Will Qt keep supporting single-touch screens too, and what will be the effects on the UI guidelines in that situation?

Problem is this: if Qt 4.6 will not backwards-support single touch, it will be very hard to start designing and implementing Qt apps on Maemo 5 right now, for both technical and economical reasons. (It will also make buyers of an N900 very unhappy to get a device that will be obsolete next year, but that's a bit to the side really.)

If Qt 4.6 will be able to support both single touch and multi touch screens, what then will be the consequences of this? For instance, zooming will likely to be done by pinching, but that doesn't work on single touch screens. This would mean an extra gadget for zooming in the interface, needing space etc.