bug#28621: Proposed patch for doc of posn-window and code of posn-set-point to handle frame arguments

[martin rudalics]

> ! `posn-window': The window or frame of the event end.

If we start talking about "event ends" here we should export that
concept to the remaining ‘posn-*’ functions as well.

> ! If POSITION is outside the frame where the event was initiated, return
> ! that frame instead.  POSITION should be a list of the form returned by

I suppose this is not sufficient: We get a frame also when the mouse is
on its tool or menu bar, some of ist borders ...

But note that I've never been able to understand the purpose of these
‘posn-*’ functions and they usually confuse the hell out of me.  IMHO it
would make much more sense to declare them obsolete and concentrate on
describing event structures better.

martin