bug#50141: Current part of emacs red, other parts blue

bug#50141: Current part of emacs red, other parts blue

[積丹尼 Dan Jacobson]

$ emacs
C-x 2
C-x 3
C-x 2
C-x 3
We have chopped the screen into little chunks.
It would be nice to have the current chunk's background e.g., red,
and the other chunks' blue.
https://stackoverflow.com/questions/33195122/highlight-current-active-window
didn't work for me.

bug#50141: Current part of emacs red, other parts blue

[Eli Zaretskii]

> From: 積丹尼 Dan Jacobson
>  <jidanni@jidanni.org>
> Date: Sat, 21 Aug 2021 14:05:45 +0800
> 
> $ emacs
> C-x 2
> C-x 3
> C-x 2
> C-x 3
> We have chopped the screen into little chunks.
> It would be nice to have the current chunk's background e.g., red,
> and the other chunks' blue.
> https://stackoverflow.com/questions/33195122/highlight-current-active-window
> didn't work for me.

Emacs's way to mark the current window is by changing the way the mode
line is displayed.

bug#50141: Current part of emacs red, other parts blue

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

> Emacs's way to mark the current window is by changing the way the mode
> line is displayed.

There's also `cursor-in-non-selected-windows', which is another
kinda-sorta subtle indicator.

However, Dan's request has come up a number of times (e.g., bug#12056,
which I'm merging this with), so I'm wondering whether we should add
something like this...  or at least add some infrastructure that would
allow it.

The obvious thing would be to run something from `select-window', but I
don't see any obvious hook that we could be using there.  Am I missing
something?  I was thinking about adding a minor mode for changing
background colours in windows...

On the other hand, if we want to add this, perhaps it'd make more sense
to just add a new variable to change the background colour of
non-selected backgrounds directly.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#50141: Current part of emacs red, other parts blue

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: 積丹尼 Dan Jacobson <jidanni@jidanni.org>,
>   50141@debbugs.gnu.org
> Date: Sat, 21 Aug 2021 14:48:01 +0200
> 
> However, Dan's request has come up a number of times (e.g., bug#12056,
> which I'm merging this with), so I'm wondering whether we should add
> something like this...  or at least add some infrastructure that would
> allow it.
> 
> The obvious thing would be to run something from `select-window', but I
> don't see any obvious hook that we could be using there.  Am I missing
> something?  I was thinking about adding a minor mode for changing
> background colours in windows...

buffer-list-update-hook sounds like that infrastructure.

bug#50141: Current part of emacs red, other parts blue

[Eli Zaretskii]

> Date: Sat, 21 Aug 2021 16:12:41 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: 50141@debbugs.gnu.org, jidanni@jidanni.org
> 
> > From: Lars Ingebrigtsen <larsi@gnus.org>
> > Cc: 積丹尼 Dan Jacobson <jidanni@jidanni.org>,
> >   50141@debbugs.gnu.org
> > Date: Sat, 21 Aug 2021 14:48:01 +0200
> > 
> > However, Dan's request has come up a number of times (e.g., bug#12056,
> > which I'm merging this with), so I'm wondering whether we should add
> > something like this...  or at least add some infrastructure that would
> > allow it.
> > 
> > The obvious thing would be to run something from `select-window', but I
> > don't see any obvious hook that we could be using there.  Am I missing
> > something?  I was thinking about adding a minor mode for changing
> > background colours in windows...
> 
> buffer-list-update-hook sounds like that infrastructure.

But I think the real problem is how to define a window-specific
default face.  It's not easy, and I'm not sure it will work.
Something using the :filtered thingy, I guess?  But I'm not sure it
will work for the default face.

Basically, faces were never designed to be window-specific.  Even
making them buffer-specific (via face-remapping-alist) is somewhat
tricky.

bug#50141: Current part of emacs red, other parts blue

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

> buffer-list-update-hook sounds like that infrastructure.

But it's only run if NORECORD is nil...  But I guess that only happens
when we're not really displaying the window, but only selecting it to
select back to something else before the user notices?  So using it
should perhaps work...

Eli Zaretskii <eliz@gnu.org> writes:

> But I think the real problem is how to define a window-specific
> default face.  It's not easy, and I'm not sure it will work.
> Something using the :filtered thingy, I guess?  But I'm not sure it
> will work for the default face.
>
> Basically, faces were never designed to be window-specific.  Even
> making them buffer-specific (via face-remapping-alist) is somewhat
> tricky.

Yeah, I suspect we can't use faces here, but might have to add some new
window-specific background colour setting?  Which might be generally
useful, anyway.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#50141: Current part of emacs red, other parts blue

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: jidanni@jidanni.org,  50141@debbugs.gnu.org
> Date: Sat, 21 Aug 2021 15:28:25 +0200
> 
> > Basically, faces were never designed to be window-specific.  Even
> > making them buffer-specific (via face-remapping-alist) is somewhat
> > tricky.
> 
> Yeah, I suspect we can't use faces here, but might have to add some new
> window-specific background colour setting?

What could that color setting be, except some face attribute?

bug#50141: Current part of emacs red, other parts blue

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

>> Yeah, I suspect we can't use faces here, but might have to add some new
>> window-specific background colour setting?
>
> What could that color setting be, except some face attribute?

I don't know -- I haven't actually looked at how this could be
implemented.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#50141: Current part of emacs red, other parts blue

[martin rudalics]

 >> buffer-list-update-hook sounds like that infrastructure.

`window-selection-change-functions' please.

 > But I think the real problem is how to define a window-specific
 > default face.  It's not easy, and I'm not sure it will work.
 > Something using the :filtered thingy, I guess?  But I'm not sure it
 > will work for the default face.
 >
 > Basically, faces were never designed to be window-specific.  Even
 > making them buffer-specific (via face-remapping-alist) is somewhat
 > tricky.

Here I can write

(set-window-face-remapping-alist nil '((default (:background "yellow") default)))

It was pretty trivial to implement but lifting it from the rest of my
changes might be non-trivial.  If people are very, very interested, I
can give it a try.

martin

bug#50141: Current part of emacs red, other parts blue

[Eli Zaretskii]

> Cc: 50141@debbugs.gnu.org, jidanni@jidanni.org
> From: martin rudalics <rudalics@gmx.at>
> Date: Sat, 21 Aug 2021 15:55:57 +0200
> 
> (set-window-face-remapping-alist nil '((default (:background "yellow") default)))
> 
> It was pretty trivial to implement but lifting it from the rest of my
> changes might be non-trivial.  If people are very, very interested, I
> can give it a try.

But the request here is not to do this for a particular window, the
request is to do this for _any_ window when it is selected.

bug#50141: Current part of emacs red, other parts blue

[Gregory Heytings]

>
> I don't know -- I haven't actually looked at how this could be 
> implemented.
>

It is already implemented AFAICS:

(require 'auto-dim-other-buffers)
(set-face-attribute 'default nil :background "red")
(set-face-attribute 'auto-dim-other-buffers-face nil :background "blue")
(auto-dim-other-buffers-mode 1)

It uses the :filtered feature introduced in Emacs 27.

bug#50141: Current part of emacs red, other parts blue

[Lars Ingebrigtsen]

Gregory Heytings <gregory@heytings.org> writes:

> It is already implemented AFAICS:
>
> (require 'auto-dim-other-buffers)
> (set-face-attribute 'default nil :background "red")
> (set-face-attribute 'auto-dim-other-buffers-face nil :background "blue")
> (auto-dim-other-buffers-mode 1)
>
> It uses the :filtered feature introduced in Emacs 27.

Oh, cool.  I guess there isn't more to do here, then...

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#50141: Current part of emacs red, other parts blue

[Lars Ingebrigtsen]

martin rudalics <rudalics@gmx.at> writes:

> Here I can write
>
> (set-window-face-remapping-alist nil '((default (:background "yellow")
> default)))
>
> It was pretty trivial to implement but lifting it from the rest of my
> changes might be non-trivial.  If people are very, very interested, I
> can give it a try.

Could be interesting...

Eli Zaretskii <eliz@gnu.org> writes:

> But the request here is not to do this for a particular window, the
> request is to do this for _any_ window when it is selected.

It'd be used by a (minor) mode that'd loop over all windows on a
window selection change, I'd have thought?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#50141: Current part of emacs red, other parts blue

[martin rudalics]

 > But the request here is not to do this for a particular window, the
 > request is to do this for _any_ window when it is selected.

We'd have to add a minor mode that puts its function on
`window-selection-change-functions'.  That function would simply move
the background from the old selected window to the new selected window
like

(set-window-face-remapping-alist
  (old-selected-window) '((default (:background nil) default)))
(set-window-face-remapping-alist
  nil '((default (:background background-of-selected-window) default)))

What else would we want?

martin

bug#50141: Current part of emacs red, other parts blue

[martin rudalics]

 >> It is already implemented AFAICS:
 >>
 >> (require 'auto-dim-other-buffers)
 >> (set-face-attribute 'default nil :background "red")
 >> (set-face-attribute 'auto-dim-other-buffers-face nil :background "blue")
 >> (auto-dim-other-buffers-mode 1)
 >>
 >> It uses the :filtered feature introduced in Emacs 27.
 >
 > Oh, cool.  I guess there isn't more to do here, then...

I doubt it would work when showing the same buffer in two windows.

martin

bug#50141: Current part of emacs red, other parts blue

[Lars Ingebrigtsen]

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martin rudalics <rudalics@gmx.at> writes:

>>> (require 'auto-dim-other-buffers)
>>> (set-face-attribute 'default nil :background "red")
>>> (set-face-attribute 'auto-dim-other-buffers-face nil :background "blue")
>>> (auto-dim-other-buffers-mode 1)
>>>
>>> It uses the :filtered feature introduced in Emacs 27.
>>
>> Oh, cool.  I guess there isn't more to do here, then...
>
> I doubt it would work when showing the same buffer in two windows.

I downloaded the package to test it now, and somehow it does:


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Active *scratch* on the top, and then two non-active windows (dimmed)
with *scratch* on the bottom.

I haven't actually looked at the code to see what it does...

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#50141: Current part of emacs red, other parts blue

[martin rudalics]

> Active *scratch* on the top, and then two non-active windows (dimmed)
> with *scratch* on the bottom.
>
> I haven't actually looked at the code to see what it does...

Seems to work.  I didn't know about the :filtered face attribute.

martin

bug#50141: Current part of emacs red, other parts blue

[Eli Zaretskii]

> From: martin rudalics <rudalics@gmx.at>
> Date: Sat, 21 Aug 2021 17:23:00 +0200
> Cc: Gregory Heytings <gregory@heytings.org>, 50141@debbugs.gnu.org,
>  jidanni@jidanni.org
> 
> I didn't know about the :filtered face attribute.

It's a relatively new addition, and is rarely used.

bug#50141: Current part of emacs red, other parts blue

[Gregory Heytings]

>> I didn't know about the :filtered face attribute.
>
> It's a relatively new addition, and is rarely used.
>

FWIW, I use it all the time, through the auto-dim-other-buffers package.

bug#50141: Current part of emacs red, other parts blue

[Juri Linkov]

> However, Dan's request has come up a number of times (e.g., bug#12056,
> which I'm merging this with), so I'm wondering whether we should add
> something like this...  or at least add some infrastructure that would
> allow it.
>
> The obvious thing would be to run something from `select-window', but I
> don't see any obvious hook that we could be using there.  Am I missing
> something?  I was thinking about adding a minor mode for changing
> background colours in windows...
>
> On the other hand, if we want to add this, perhaps it'd make more sense
> to just add a new variable to change the background colour of
> non-selected backgrounds directly.

There was a similar request recently in bug#49844 to highlight
the active non-selected minibuffer only.  The latest patch uses
window-selection-change-functions and adds a window-local overlay
with a special face.

Adding a new variable would be nice to generalize such feature.
When it will contain a face name, then the minibuffer could set
it buffer-locally, so it will affect only the minibuffer for bug#49844.

bug#50141: Current part of emacs red, other parts blue

[Lars Ingebrigtsen]

Juri Linkov <juri@linkov.net> writes:

> Adding a new variable would be nice to generalize such feature.
> When it will contain a face name, then the minibuffer could set
> it buffer-locally, so it will affect only the minibuffer for bug#49844.

Yeah, that would be pretty nice.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no