Re: mwheel scroll horizontally

[Juri Linkov <juri@jurta.org>]

>> Why mwheel.el doesn't allow horizontal scrolling?
>
> You mean: why doesn't it *support* horizontal scrolling?
> Lack of a corresponding patch, I guess ;-)
>
>> For instance, Gimp allows the Shift modifier to change
>> the direction of scrolling from vertical to horizontal.
>
> There are also various situations where the user has access to "real"
> horizontal scrolling.  So rather than a modifier, it might be that
> horizontal scrolling is specified by mouse-6 and mouse-7 or yet
> something else.

Yes, mwheel.el is limited in this regard too and supports only
a monowheel mouse.

>> Shift and Control are already in use in mouse-wheel-scroll-amount,
>> but Meta is available.  What about using Meta for horizontal
>
> Doing it via global-map key bindings doesn't sound quite right.
> Instead, we want to have mwheel understand wheel-left and wheel-right
> events, and then (if/when needed) remap (via function-key-map) other
> events to those ones.

Maybe something like (in bindings.el or in term/x-win.el):

  (define-key function-key-map [mouse-4]   [wheel-down])
  (define-key function-key-map [mouse-5]   [wheel-up])
  (define-key function-key-map [mouse-6]   [wheel-right])
  (define-key function-key-map [mouse-7]   [wheel-left])
  (define-key function-key-map [M-mouse-6] [wheel-right])
  (define-key function-key-map [M-mouse-7] [wheel-left])

Actually, mwheel.el contains:

  (defcustom mouse-wheel-down-event
    (if (or (featurep 'w32-win) (featurep 'ns-win))
        'wheel-up

Does this mean that w32-win and ns-win already generate
these events instead of mouse-4 and mouse-5?  Could someone
with access to these systems with a two-wheeled mouse
please tell what events they generate for the second wheel?