Re: mouse-drag-and-drop-region

[Stefan Monnier]

>> render buffer text to desired-glyph-matrix
>> combine desired-glyph-matrix with overlay-matrix into combined-matrix
>> send combined-matrix to screen
> If you mean that literally, then the above will disable (almost) all
> redisplay optimizations, and will cause Emacs always to display each
> window in its entirety.
> Redisplay optimizations require that Emacs be
> able to _reason_ about parts of the window display being unchanged, by
> looking at the related objects and variables -- buffers, overlays,
> etc.

The above is the *model*.  I'd describe the current model as:

    render buffer text to glyph-matrix
    send glyph-matrix to screen

both models are amenable to various optimizations.  Most of the
optimizations applicable to the current model should be applicable to
the other as well.


        Stefan