Re: scroll-down with pixel transition

[Tak Kunihiro]

>> Let's say the lines above give smooth scrolling.  If so, to make Emacs
>> scroll both up and down with pixel-to-pixel resolution, requirement is
>> that `set-window-vscroll' accepts negative number.
> 
> Like I explained, it won't help, because the moment you do something
> that potentially requires a redisplay, the vscroll will be zeroed, and
> the text will scroll back to the state where the first screen line
> visible in the window is fully visible.  So this cannot be the
> solution to your problem, I think.

I think before pixel-level vertical scrolling up or down,
scrolling single line up or down `with pixel transition' should be
implemented.  It ends up (window-vscroll nil t) to be zero.
This may be good enough to give modern feel.

I assign the snippet to mwheel-scroll-up-function and it works
OK so far.