bug#9541: mouse-1 inside scroll-margin causes undesirable region activation

[Stefan Monnier <monnier@iro.umontreal.ca>]

> Here is my work-around.  I don't fully understand the ramifications of
> doing this, but so far it seems work.

> (defun le::mouse-drag-region (event)
>   "mouse-drag-region but clickable in scroll-margin"
>   (interactive "e")
>   (let ((scroll-margin 0))
>     (mouse-drag-region event)))

But this goes against the definition of scroll-margin which does not
make any exception for mouse events.

An alternative would be to declare that scroll-margin does not apply to
commands when run via mouse events.

This said, the current behavior of scroll-margin is clearly problematic
and even buggy (e.g. it seems that displaying the EOB prevents the
mouse-clicks from causing a scroll, even when that scroll would be
towards the BOB).


        Stefan