RE: mwheel scroll horizontally

["Drew Adams" <drew.adams@oracle.com>]

> > That's the wrong place for such control, IMO.  I mean that 
> > it shouldn't be hard-coded like that.  We should leave S-
> > and C- open for use with the wheel, and not hard-code them
> > to representing a scroll amount.
> 
> The Commentary in mwheel.el says:
> 
>   ;; I for one would prefer some way of converting the button4/button5
>   ;; events into different event types, like 'mwheel-up' or
>   ;; 'mwheel-down', but I cannot find a way to do this very easily (or
>   ;; portably), so for now I just live with it.
> 
> Is it what you mean?

No. I think that's something different.

I just meant that the option in question (whatever it's called) should not
decide once and for all, by the values it offers, that users can use S- and C-
for vertical scrolling and M- for horizontal scrolling, and it should not decide
once and for all that users can choose two scroll amounts for vertical scrolling
but only one amount for horizontal scrolling.  All possibilities should be open
to users.

My point was only that the user option should let users pick any combination of
modifiers and amounts for vertical and horizontal.  Choose a default
combination, OK, but don't hem in the user wrt the modifiers, scroll directions,
amounts (or even wheel direction: which wheel direction (up/down) maps to which
scroll direction (up/down - or left/right)).

Make the option as general as possible, while still making it easy to choose a
value.

> > There is nothing sacred about window scrolling - a mouse 
> > wheel can do lots more interesting things in Emacs than
> > scroll a window.
> 
> Yes, they are not just about scrolling.  For instance, in Gimp/Chrome
> C-mwheel zooms in/out (like `C-x C-+' `C-x C--' 
> `text-scale-adjust' in Emacs).

Yes.  My only point there was that sometimes users and library writers can
mistakenly get the impression that bindings we provide by default (e.g. the
wheel is bound for scrolling) are not to be overridden.  Anything we can do to
dispel such an impression helps.