bug#33694: 27.0.50; 'set-window-scroll-bars' broken

bug#33694: 27.0.50; 'set-window-scroll-bars' broken

[martin rudalics]

This change

2015-09-30  Stefan Monnier  <monnier@iro.umontreal.ca>

	Try to avoid redisplaying all frames when creating a new one

	...

	* src/window.c (apply_window_adjustment): Remove redundant setting of
	windows_or_buffers_changed.

         ...

broke evaluating the following form with emacs -Q:

(set-window-scroll-bars nil 0 nil)

This should immediately remove the scroll bar of the selected window
but instead hides its right fringe under the scroll bar.

martin

bug#33694: 27.0.50; 'set-window-scroll-bars' broken

[Eli Zaretskii]

> Date: Mon, 10 Dec 2018 09:41:11 +0100
> From: martin rudalics <rudalics@gmx.at>
> Cc: monnier@iro.umontreal.ca
> 
> This change
> 
> 2015-09-30  Stefan Monnier  <monnier@iro.umontreal.ca>
> 
> 	Try to avoid redisplaying all frames when creating a new one
> 
> 	...
> 
> 	* src/window.c (apply_window_adjustment): Remove redundant setting of
> 	windows_or_buffers_changed.
> 
>          ...
> 
> broke evaluating the following form with emacs -Q:
> 
> (set-window-scroll-bars nil 0 nil)
> 
> This should immediately remove the scroll bar of the selected window
> but instead hides its right fringe under the scroll bar.

Does the below look reasonable?  I'd like to apply it to the emacs-26
branch.

diff --git a/src/window.c b/src/window.c
index 5d99098..c93ab5c 100644
--- a/src/window.c
+++ b/src/window.c
@@ -7254,6 +7254,10 @@ set_window_scroll_bars (struct window *w, Lisp_Object width,
   wset_horizontal_scroll_bar_type (w, Qnil);
 #endif
 
+  /* This is needed to trigger immediate redisplay of the window when
+     scroll bars are changed.  */
+  if (changed)
+    windows_or_buffers_changed = 31;
   return changed ? w : NULL;
 }
 

bug#33694: 27.0.50; 'set-window-scroll-bars' broken

[martin rudalics]

 > Does the below look reasonable?  I'd like to apply it to the emacs-26
 > branch.

Hmm...  'set-window-fringes' has the same problem.

martin

bug#33694: 27.0.50; 'set-window-scroll-bars' broken

[Eli Zaretskii]

> Date: Mon, 10 Dec 2018 18:44:38 +0100
> From: martin rudalics <rudalics@gmx.at>
> CC: 33694@debbugs.gnu.org, monnier@iro.umontreal.ca
> 
>  > Does the below look reasonable?  I'd like to apply it to the emacs-26
>  > branch.
> 
> Hmm...  'set-window-fringes' has the same problem.

I can do the same there.  Anything else?

bug#33694: 27.0.50; 'set-window-scroll-bars' broken

[martin rudalics]

 >> Hmm...  'set-window-fringes' has the same problem.
 >
 > I can do the same there.  Anything else?

Since IIUC margins are handled differently I see no further issues.

Thanks for fixing these, martin

bug#33694: 27.0.50; 'set-window-scroll-bars' broken

[Eli Zaretskii]

> Date: Tue, 11 Dec 2018 09:34:57 +0100
> From: martin rudalics <rudalics@gmx.at>
> CC: 33694@debbugs.gnu.org, monnier@iro.umontreal.ca
> 
>  >> Hmm...  'set-window-fringes' has the same problem.
>  >
>  > I can do the same there.  Anything else?
> 
> Since IIUC margins are handled differently I see no further issues.

OK, but can you give me a recipe for set-window-fringes?  In my
testing, the fringes are updated instantly after the call.

Thanks.

bug#33694: 27.0.50; 'set-window-scroll-bars' broken

[martin rudalics]

 > OK, but can you give me a recipe for set-window-fringes?  In my
 > testing, the fringes are updated instantly after the call.

When on the release branch with emacs -Q I evaluate

(set-window-fringes nil 40 60)

in *scratch* I don't see any change.  After moving the cursor I do.

martin

bug#33694: 27.0.50; 'set-window-scroll-bars' broken

[Eli Zaretskii]

> Date: Tue, 11 Dec 2018 10:05:41 +0100
> From: martin rudalics <rudalics@gmx.at>
> CC: 33694@debbugs.gnu.org, monnier@iro.umontreal.ca
> 
>  > OK, but can you give me a recipe for set-window-fringes?  In my
>  > testing, the fringes are updated instantly after the call.
> 
> When on the release branch with emacs -Q I evaluate
> 
> (set-window-fringes nil 40 60)
> 
> in *scratch* I don't see any change.  After moving the cursor I do.

Thanks, I pushed the changes to the emacs-26 branch.

bug#33694: 27.0.50; 'set-window-scroll-bars' broken

[martin rudalics]

 > Thanks, I pushed the changes to the emacs-26 branch.

Thank you, martin