Re: mouse wheel support in Emacs 21.3.50

[Stefan Monnier <monnier@iro.umontreal.ca>]

> 2. What is the latest mouse wheel support? In this version of Emacs
> (21.3.50.1), I see mwheel code with no version number, copyright ... 2002.
> Is that the latest? Is there any doc for this, besides the source code
> comments?

I'm not sure what you mean by "latest mouse wheel support".
If you're asking about development external to Emacs, I don't don't know of
any such thing.

> 3. I'd like to know how to interpret the components of the various mouse
> events. In Emacs 20 this was simple; there was just the POSITION and the
> DELTA. Now I see lots of components (with no Elisp Info) - what does each
> mean? In particular, if I call read-event and get mouse wheel events, where
> can I get the DELTA info that used to be there?

I don't know w32, so double check it, but I believe you can extract it with
event-click-count.

> And the whole treatment of the wheel as buttons 4 & 5 is not clear to me.

AFAIK it only affects X11.

> I can see that mouse-4 and mouse-5 are correctly bound to real buttons, so
> what is their relation to wheeling?

Most Xservers are configured to map wheel events to mouse-4 and mouse-5.

> 5. Finally, although I have little real hope for this, are there any
> guidelines for trying to make code that deals with making the mouse wheel
> work in both Emacs 20 and 21?

Not that I know, and it's likely to still change in the future, at least
on X11.  What are you trying to do?  I worked on the mwheel.el code, so
I can probably help.
Note that it's not new: there was no guideline before on making mouse wheel
code work on both X11 and w32.  Now at least, it's a bit easier (tho it's
still undocumented).


        Stefan