Buttons in Customize buffers

Buttons in Customize buffers

[Eli Zaretskii]

Buttons in Customize buffers used to have a special mouse-face, but
that was removed in favor of changing the mouse pointer shape by this
change:

    2004-06-08  Kim F. Storm  <storm@cua.dk>

	    * wid-edit.el (widget-specify-button): Use hand pointer rather
	    than mouse-face as visible mouse-over effect.

That is okay for graphics displays, but not for mouse-capable text
terminals, since the latter cannot change the mouse pointer shape.
The MS-DOS terminal is one case, but I'm guessing that non-windows
sessions on an xterm with xt-mouse loaded are suffering from the same
problem.

Is the following change okay to install?

Index: lisp/wid-edit.el
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/wid-edit.el,v
retrieving revision 1.134
diff -u -r1.134 wid-edit.el
--- lisp/wid-edit.el	27 Dec 2004 16:38:57 -0000	1.134
+++ lisp/wid-edit.el	22 Jan 2005 11:22:52 -0000
@@ -391,7 +391,11 @@
     (overlay-put overlay 'evaporate t)
     ;; We want to avoid the face with image buttons.
     (unless (widget-get widget :suppress-face)
-      (overlay-put overlay 'face (widget-apply widget :button-face-get)))
+      (overlay-put overlay 'face (widget-apply widget :button-face-get))
+      ; Text terminals cannot change mouse pointer shape, so use mouse
+      ; face instead.
+      (or (display-graphic-p)
+	  (overlay-put overlay 'mouse-face widget-mouse-face)))
     (overlay-put overlay 'pointer 'hand)
     (overlay-put overlay 'follow-link follow-link)
     (overlay-put overlay 'help-echo help-echo)))

Re: Buttons in Customize buffers

[Stefan Monnier]

> That is okay for graphics displays, but not for mouse-capable text
> terminals, since the latter cannot change the mouse pointer shape.
> The MS-DOS terminal is one case, but I'm guessing that non-windows
> sessions on an xterm with xt-mouse loaded are suffering from the same
> problem.

> Is the following change okay to install?

Could the MS-DOS code be changed to recognize the `pointer' property and do
something with it?  Maybe by adding a ms-dos-pointer-to-mouse-face-alist
that tells which mouse-face to use for which value of `pointer'?


        Stefan

Re: Buttons in Customize buffers

[Eli Zaretskii]

> Cc: emacs-devel@gnu.org
> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Date: Sat, 22 Jan 2005 11:12:47 -0500
> 
> Could the MS-DOS code be changed to recognize the `pointer' property and do
> something with it?

It could, but why?  What is the purpose of emulating pointer shape
change with something utterly unrelated?  That could bite us down the
road, if some Lisp code changes the mouse pointer to signal something
other than a link.

Are there any downsides to my suggested patch?

Re: Buttons in Customize buffers

[Stefan Monnier]

>> Could the MS-DOS code be changed to recognize the `pointer' property and do
>> something with it?

> It could, but why?  What is the purpose of emulating pointer shape
> change with something utterly unrelated?  That could bite us down the
> road, if some Lisp code changes the mouse pointer to signal something
> other than a link.

> Are there any downsides to my suggested patch?

I didn't mean it as an alternative to your patch.


        Stefan

Re: Buttons in Customize buffers

[Eli Zaretskii]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Date: Sat, 22 Jan 2005 11:41:29 -0500
> Cc: emacs-devel@gnu.org
> 
> I didn't mean it as an alternative to your patch.

Sorry, I misunderstood you, then.

Were you suggesting a way to implement mouse pointer shape control in
the MS-DOS port?  If so, I decided long ago not to, as I didn't see
any reasonable way to do that, and didn't think the DOS port is
important enough to have this feature.

The gory details are that on plain DOS machine, there's a system call
to modify the pointer shape into something other than a horizontal bar
of some height, but doing so causes the character under the pointer to
become unreadable (it's replaced by the mouse pointer).  On Windows
(and most DJGPP users run DJGPP programs on Windows these days), the
mouse pointer is what Windows creates, and I know of no way for a DOS
program to request that the pointer shape be changed.  Faced with
these problems, I decided not to implement the feature.

If someone has ideas how to implement this, I'm all ears.  I'd also
consider some emulation, but the emulation should have some
resemblance to the mouse pointer, not to the text it hovers above.

TIA

Re: Buttons in Customize buffers

[Kim F. Storm]

"Eli Zaretskii" <eliz@gnu.org> writes:

> Is the following change okay to install?

I don't see any problem with it.

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

Re: Buttons in Customize buffers

[Eli Zaretskii]

> Cc: emacs-devel@gnu.org
> From: storm@cua.dk (Kim F. Storm)
> Date: Sun, 23 Jan 2005 00:39:03 +0100
> 
> "Eli Zaretskii" <eliz@gnu.org> writes:
> 
> > Is the following change okay to install?
> 
> I don't see any problem with it.

Thanks for the feedback.  Committed.