Re: Additional cleanup around xterm-mouse

[Jared Finder]

On 2020-11-18 9:40 am, Eli Zaretskii wrote:
> > Date: Sun, 15 Nov 2020 22:29:20 -0800
> > From: Jared Finder <jared@finder.org>
> > Cc: emacs-devel@gnu.org
> >
> > Creating such an alternative function doesn't appear too bad if you're
> > okay with having the same run-with-idle-timer pattern that read-key
> > uses.  I do not think it can be xterm specific as it needs to apply 
> > all
> > of input-decode-map to be able to return function keys such as [f1] on 
> > a
> > native Linux term or an xterm.  (This is important for
> > widget-key-sequence-read-event.)
>
> I don't think I follow.  All the places where you need changes are
> related to handling mouse events, so why cannot it be specific to
> xt-mouse?

There is a bug in widget-key-sequence-read-event's usage of keyboard 
events specifically.

The function widget-key-sequence-read-event currently does not correctly 
translate function keys for the terminal.  It has code that attempts to 
apply function-key-map, but does not apply input-decode-map, so it can 
not read function keys.  (Additionally, it should be using 
local-function-key-map now.)  Try the following steps.

Git revision: d5ac66
TERM env var: linux

Run "emacs -Q"
M-x load-library RET outline RET
M-x customize-variable RET outline-minor-mode-prefix RET
Move the cursor into the editable field.
C-q (runs the command widget-key-sequence-read-event)
Press f1.

I get the untranslated escape code sequence for [f1] put in.
I should get [f1].

Changing to read-key fixes this as read-key goes through 
read-key-sequence which applies input-decode-map.  However, to get the 
same intended functionality requires some new parameters, which I also 
add in my patch.

And as a point of history, widget-key-sequence-read-event appears to 
have been added in Jan 2006, and input-decode-map was added in Oct 2007.

> > An alternative is to just use read-key as is in most cases and make my
> > change a parameter / special variable.  Most of my patch's changes 
> > work
> > fine with the existing behavior of read-key.  Only the following 
> > changes
> > do not:
> >
> > * lisp/vc/ediff-wind.el (ediff-get-window-by-clicking)
> > ==> As coded, expects the first mouse event returned by read-event to 
> > be
> > a down-mouse-X event, which it then follows by another call to
> > read-event to get the mouse-X event.  It could be easily changed to 
> > only
> > look for the up event.
> >
> > * lisp/strokes.el (strokes-read-stroke, strokes-read-complex-stroke)
> > * lisp/textmodes/artist.el (artist-mode-draw-poly)
> > ==> These both expect to detect a mix of down-mouse-X and mouse-X
> > events.
> >
> > * lisp/wid-edit.el (widget-key-sequence-read-event)
> > ==> This w/o changes to read-key, but with a behavior change.  With no
> > changes to read-key it returns just a single up event.  Currently on
> > other environments you get both a down and up event (e.g. 
> > <down-mouse-1>
> > <mouse-1>).
>
> I think I like this latter alternative better.  It is slightly less
> elegant, but simpler and less risky.  Can you show a draft of a patch
> along those lines?

Attached.  I added additional parameters to read-key. only strokes.el, 
artist.el, and wid-edit.el use the additional parameters.  Let me know 
what you think of this structure.  There's still further cleanup to do 
(add docs, clean up parameter names, etc.), that I'll do after you're 
happy with the structure.

  -- MJF

0001-WIP-Make-libraries-work-with-xterm-mouse-mode.patch
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