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

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

[Le Wang]

Repro:

1. emacs -Q
2. eval:

  (setq scroll-margin 5)

3. open some multi-page file
4. left-click in bottom margin (bottom 5 lines)

Notice region is selected and active.

This problem is noted here: http://www.emacswiki.org/emacs/SmoothScrolling

A package attempts to solve it here:
http://adamspiers.org/computing/elisp/smooth-scrolling.el

But the bug is in Emacs.

-- 
Le

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

[Le Wang]

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)))

(global-set-key [(down-mouse-1)] 'le::mouse-drag-region)

-- 
Le

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

[Stefan Monnier]

> 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

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

[Johan Bockgård]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

> 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).

The real bug is that mouse-clicks set the mark (always). (Search for
push-mark in mouse-drag-track.)

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

[Chong Yidong]

Johan Bockgård <bojohan@gnu.org> writes:

> Stefan Monnier <monnier@iro.umontreal.ca> writes:
>
>> 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).
>
> The real bug is that mouse-clicks set the mark (always). (Search for
> push-mark in mouse-drag-track.)

No, that's intended behavior.  The OP's suggestion of disabling the
scroll margin while tracking a mouse drag is on the right track.  I've
committed a change along those lines.

New mouse click behavior (was: bug#9541: mouse-1 inside scroll-margin causes undesirable region activation)

[Johan Bockgård]

Chong Yidong <cyd@stupidchicken.com> writes:

> Johan Bockgård <bojohan@gnu.org> writes:
>
>> The real bug is that mouse-clicks set the mark (always). (Search for
>> push-mark in mouse-drag-track.)
>
> No, that's intended behavior.  The OP's suggestion of disabling the
> scroll margin while tracking a mouse drag is on the right track.  I've
> committed a change along those lines.

I still think it's a bug. The new behavior is a pain. A mouse click
should move point; it makes no sense for it to also set the mark.

Also, there's no simple way to go back to the old, sane, behavior.

(It also causes blinking in the tool bar when you click the mouse.)

Re: New mouse click behavior

[martin rudalics]

 >>> The real bug is that mouse-clicks set the mark (always). (Search for
 >>> push-mark in mouse-drag-track.)
 >> No, that's intended behavior.  The OP's suggestion of disabling the
 >> scroll margin while tracking a mouse drag is on the right track.  I've
 >> committed a change along those lines.
 >
 > I still think it's a bug. The new behavior is a pain. A mouse click
 > should move point; it makes no sense for it to also set the mark.
 >
 > Also, there's no simple way to go back to the old, sane, behavior.
 >
 > (It also causes blinking in the tool bar when you click the mouse.)

So finally I seem to understand what causes

http://lists.gnu.org/archive/html/emacs-devel/2011-04/msg00399.html

Couldn't we make this mark setting behavior customizable?

martin