QTouchEvent::TouchPoint documentation is wrong regarding ::id()

From the docs:

"int TouchPoint::id () const
Returns the id number of this touch point.

Id numbers are globally sequential, starting at zero, meaning the first touch point in the application has id 0, the second has id 1, and so on."

This is plain wrong, and it gives the idea that a user could store the id's somehow. But there is no global sequence.

Instead, what ::id() returns is an id to the currently active touch points, ie., the position in QTouchEvent::touchPoints().
It is better to state that an id stays valid from touch event begin to touch event end, (but only if those events are received on the same active touch point). After a touch event transaction ends, Qt starts to reuse the id's. With other words: all id's get invalidated after an active touchpoint enters its TouchPointReleased state.