XComposite input redirection/transformation proposal

[Xavier Bestel]

On Mon, 2008-02-18 at 20:29 -0800, Keith Packard wrote:
> You need full bijection between every window and the screen coordinate
> space (expressed as nested bijections between windows and their
> parents). Otherwise, grabs will have incorrect coordinates (making
> selections and scrollbars work in 'odd' ways). Fixing drag&drop may also
> be an adventure. 

I fear it's not possible. Compositing managers allow windows to be
displayed multiple times (e.g. once in the pager, once normally) and
some allow even more weird multiple instances of the same window (take a
look at Metisse). I'm sure one day they'll want to enable input on some
or all of these instances, meaning bijection isn't an option.

You could hack around it: when grab starts, identify which instance it
started from and limit redirection from there. So you'd need bijection
only during grabs. But it may not always work.