Scroll behavior on MS-Windows

[Bram Moolenaar]

While making the scroll wheel work in popup windows I noticed that the
scroll wheel actually works differently on MS-Windows from other
systems. In most places the window under the mouse pointer is scrolled.
On MS-Windows the window with focus is scrolled.

I don't recall this being reported as a bug, thus I suppose we should
enable the behavior with an option. We already have 'mousefocus' thus a
logical choice would be 'scrollfocus'.

We could theoretically also implement it for non-MS-Windows systems, but
with the default "on". Not sure how useful that is, thus I'll leave it
for later.

For MS-Windows the default would be "off" to keep it backwards
compatible. I imagine MS-Windows users are used to this behavior (I
actually have the problem in Explorer to scroll the left panel while I
want to scroll the right panel).

Any remarks?

--
The only backup you need is the one that you didn't have time for.
(Murphy)

/// Bram Moolenaar -- Br...@Moolenaar.net -- http://www.Moolenaar.net \\\
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