Should the mode line extend under the scroll bar?

Should the mode line extend under the scroll bar?

[Richard Stallman]

The change that was made in how far the mode line extends
has practical effects that this user is unhappy with.
what do others think?

From: "Drew Adams" <drew.adams@oracle.com>
...

In Emacs 20, the mode line did not extend under a vertical scroll bar (or
under a vertical line) -- there was a small (~4mm) square that you could
drag with the mouse to resize the window.

In Emacs 21, this small but visible "drag handle" has disappeared. If you
position the mouse _very_ carefully along the mode line at the window
division, you can grab and drag the divider. However, this effective drag
handle is _very_ small and not obvious at all (only the cursor change
indicates its presence).

Also, if you have two horizontally adjacent windows and try to drag the
divider, you actually need to place the mouse slightly to the right of the
divider, so that it is well over the right mode line, not the left (even
though it is the left mode line that extends under the scroll bar). This is
not intuitive at all.

If you try to grab & drag directly under the scroll bar (as in Emacs 20),
you grab the left mode line, and nothing happens (no drag cursor). If you
grab slightly to the right of this, at the right edge of the scroll bar, in
the modeline (that is, _at_ the vertical line that separates the windows),
then you see the drag cursor (so everything looks OK), but you also get this
error message: "Attempt to drag leftmost scrollbar".

There is no reason for this. Intuitively, that is just what you _want_ to
do: drag the "leftmost" scrollbar - that is, drag the only vertical
separation you see between the two windows. You certainly don't want to (and
cannot) drag the _rightmost_ scrollbar/vertical line!

To be able to drag the vertical line, you must in fact grab it slightly to
the right of the visible vertical line, that is, to the right of the right
edge of the scroll bar, so that you are well over the right mode line. The
proper position appears to be at the right edge of the fringe! Dragging here
also activates the right mode line, for no reason that I can see. All of
this is not very intuitive.

RE: Should the mode line extend under the scroll bar?

[Drew Adams]

Just to clarify (I sent an update to bug-gnu-emacs, but not to this list):

Some of what I described below was due to a bug that I have not been able to
reproduce. In particular:

 - Forget about the "Attempt to drag leftmost scrollbar" bug.
 - Forget too about the complaint that the drag handle is in the wrong place
(too far to the right).

The points I want to make are just these:

 - The drag handles are not obvious (they appear only on mouseover) and are
difficult to grab (at least on Windows).

 - Grabbing a drag handle selects and activates the mode line (to its
left) - an irrelevant side effect.

Emacs 20:                 Emacs 21:

       M       M                 M       M
       M       M                 M       M
       M       M                 M       M
XXXXXXX.ZZZZZZZ.          XXXXXXXXZZZZZZZZ

The squares where the `.' are were visible drag handles for the windows.

And the `.' for a one-window-p window could do something else useful like
resize the frame to fit the window buffer.


-----Original Message-----
From: emacs-devel-bounces+drew.adams=oracle.com@gnu.org
[mailto:emacs-devel-bounces+drew.adams=oracle.com@gnu.org]On Behalf Of
Richard Stallman
Sent: Saturday, October 02, 2004 6:19 PM
To: emacs-devel@gnu.org
Subject: Should the mode line extend under the scroll bar?


The change that was made in how far the mode line extends
has practical effects that this user is unhappy with.
what do others think?

From: "Drew Adams" <drew.adams@oracle.com>
...

In Emacs 20, the mode line did not extend under a vertical scroll bar (or
under a vertical line) -- there was a small (~4mm) square that you could
drag with the mouse to resize the window.

In Emacs 21, this small but visible "drag handle" has disappeared. If you
position the mouse _very_ carefully along the mode line at the window
division, you can grab and drag the divider. However, this effective drag
handle is _very_ small and not obvious at all (only the cursor change
indicates its presence).

Also, if you have two horizontally adjacent windows and try to drag the
divider, you actually need to place the mouse slightly to the right of the
divider, so that it is well over the right mode line, not the left (even
though it is the left mode line that extends under the scroll bar). This is
not intuitive at all.

If you try to grab & drag directly under the scroll bar (as in Emacs 20),
you grab the left mode line, and nothing happens (no drag cursor). If you
grab slightly to the right of this, at the right edge of the scroll bar, in
the modeline (that is, _at_ the vertical line that separates the windows),
then you see the drag cursor (so everything looks OK), but you also get this
error message: "Attempt to drag leftmost scrollbar".

There is no reason for this. Intuitively, that is just what you _want_ to
do: drag the "leftmost" scrollbar - that is, drag the only vertical
separation you see between the two windows. You certainly don't want to (and
cannot) drag the _rightmost_ scrollbar/vertical line!

To be able to drag the vertical line, you must in fact grab it slightly to
the right of the visible vertical line, that is, to the right of the right
edge of the scroll bar, so that you are well over the right mode line. The
proper position appears to be at the right edge of the fringe! Dragging here
also activates the right mode line, for no reason that I can see. All of
this is not very intuitive.


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Re: Should the mode line extend under the scroll bar?

[Kim F. Storm]

"Drew Adams" <drew.adams@oracle.com> writes:

> The points I want to make are just these:
>
>  - The drag handles are not obvious (they appear only on mouseover) and are
> difficult to grab (at least on Windows).
>
>  - Grabbing a drag handle selects and activates the mode line (to its
> left) - an irrelevant side effect.
>
> Emacs 20:                 Emacs 21:
>
>        M       M                 M       M
>        M       M                 M       M
>        M       M                 M       M
> XXXXXXX.ZZZZZZZ.          XXXXXXXXZZZZZZZZ
>
> The squares where the `.' are were visible drag handles for the windows.
>
> And the `.' for a one-window-p window could do something else useful like
> resize the frame to fit the window buffer.


IMO the emacs 21 display behaviour is better as it indicates which
window the scroll bar belongs to.  This is more important with 21.4
where each window can control the position of its own scrollbar
(left/right).

However, I do think we can make the grab area some pixels wider
without too much trouble.  However, now since the modeline does extend
under the scrollbar, there may be mouse-sensitive elements on the
modeline at those positions, so we should be careful not to disrupt
the access to those elements (especially when the scrollbar is on the
left side).

RE: Should the mode line extend under the scroll bar?

[Drew Adams]

Good point. I agree that some visual means of associating the scroll bar
with its window might be a good thing.

We don't have to lump the two issues together though, and decide whether
Emacs 20 or 21 is better in this regard. We can perhaps DTRT by combining
your point with mine:

 1. Make the drag-handle affordance visible. Give some space and maybe a
graphic that indicates what it's for (e.g. the drag-handle cursor glyph).

 2. Visually associate the scroll bar with its window (not necessarily the
window's mode line.

Your point about mode-line sensitivity under the scroll bar (that is, where
the drag handle is) is precisely my second point - vertical bar dragging
should be disassociated from mode-line activation (sensitivity). This
interference is an unpleasant side effect.

So, the questions are, IMO:

 - How best to visually associate the scroll bar with its window in such a
way that this association does not interfere with vertical-line dragging?
 - How to dissociate mode-line activation (sensitivity) from vertical-line
dragging?

A drag handle "some pixels wider" is maybe a solution, but we can perhaps do
better. How successful this solution would be would need to be tested - it
depends on how small the drag-handle area is, and how easily the mode-line
sensitivity still interferes with vertical-line dragging.

If a good solution doesn't occur to us - that is, if we're ultimately forced
to choose between the two desirables #1 and #2 above, then I would choose
#1. Why? Because the scroll bar is obvious; the drag handle is not obvious.

Just trying the scroll bar out is enough to quickly teach you which window
it belongs to (though I hear your point about 21.4 and diff windows having
diff scroll-bar positions). The scroll bar is there; just try it to see
which window is affected. Without adequate real estate (and perhaps a
drag-handle graphic), however, the _existence_ of the drag handle can be
_missed entirely_.

Also, I don't think that extending the mode line under the scroll bar is a
good way to associate the two (or, what's really wanted, to associate the
scroll bar with the window). There must be a better way (if one is needed).


From: Kim F. Storm

> Emacs 20:                 Emacs 21:
>        M       M                 M       M
> XXXXXXX.ZZZZZZZ.          XXXXXXXXZZZZZZZZ
>
> The squares where the `.' are were visible drag handles for the windows.

IMO the emacs 21 display behaviour is better as it indicates which
window the scroll bar belongs to.  This is more important with 21.4
where each window can control the position of its own scrollbar
(left/right).

However, I do think we can make the grab area some pixels wider
without too much trouble.  However, now since the modeline does extend
under the scrollbar, there may be mouse-sensitive elements on the
modeline at those positions, so we should be careful not to disrupt
the access to those elements (especially when the scrollbar is on the
left side).

Re: Should the mode line extend under the scroll bar?

[Kim F. Storm]

"Drew Adams" <drew.adams@oracle.com> writes:

> Your point about mode-line sensitivity under the scroll bar (that is, where
> the drag handle is) is precisely my second point - vertical bar dragging
> should be disassociated from mode-line activation (sensitivity). This
> interference is an unpleasant side effect.

I just installed a fix which makes the vertical drag poiner <-> behave
a lot better.

Before, you could risk that dragging the mouse when the <-> pointer
was shown would not have any effect (at best), because the event was
associated with the wrong window.

Also, I installed another change which ensure that the pointer shape
does not change while you drag the mouse (i.e. it stays a <-> arrow).

-- 
Kim F. Storm <storm@cua.dk> http://www.cua.dk