[Webkit-unassigned] [Bug 26876] New: Scrolling with Trackpad causes odd behavior (different elements scroll as they come under the cursor)

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=26876

           Summary: Scrolling with Trackpad causes odd behavior (different
                    elements scroll as they come under the cursor)
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: Macintosh
        OS/Version: Mac OS X 10.5
            Status: UNCONFIRMED
          Severity: Minor
          Priority: P2
         Component: New Bugs
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: dylanryan at mac.com


When I scroll with two-finger drag on my MacBook Pro (and I presume it happens
when mouse-wheel scrolling, etc, but I cannot easily test), the object that is
scrolled is always the one directly under the cursor. For example, if I start a
scroll with the cursor over the body (or some other non-scrolling element) and
in the course of the scroll, another scrollable element comes under the cursor
(a textarea with a lot of content, a scrollable div, or the selects that allow
multiple inputs on this very page), that element starts scrolling, instead of
the page continuing to scroll. (This is very disconcerting)

This is not the behavior I expect (though I think it is how Safari has always
worked). What would be more expected is that whatever object the scroll was
initiated in (document.body, for example) is what scrolls, regardless of
whether another scrollable input happens to come under the cursor in the course
of the scroll (and if the textarea was where the scroll started, scrolling to
the bottom of it on my trackpad should not start scrolling the body)

Steps to Reproduce: 
1) Go to any page that has a scrollable area and full-page scroll bars (for
example, https://bugs.webkit.org/show_bug.cgi?id=3409, which has a long CC
list)
2) Position your cursor directly above (that is, higher on the monitor, not
above as in 'hovering') the inner scrollable area (the CC list in the example)
3) Begin scrolling down using 2-finger scrolling (or I assume a scroll wheel)

Expected results: The entire page scrolls down without stopping when the mouse
crosses the textarea.

Actual results: The page scrolls until the scrollable area comes under the
cursor, at which point the scrollable area scrolls until it reaches the bottom,
and then the page continues scrolling. (with such a short scrollable area as in
this example, this creates a visible pause or 'flicker' in the page scrolling)

Other things to try: Start with the cursor hovering over a scrollable area (the
CC list in the same bug) and scroll down. Once you hit the bottom of the
scrollable area, the page begins to scroll when it probably should not. 

As far as I know, this is not a regression, but I cannot easily test earlier
versions of Safari. Certainly, it has been like this as long as I can remember,
I just finally got annoyed enough at it to report it.

Note: Firefox (3.5.b4) on Mac and XP (actually, BootCamp on the same computer)
works as expected: Scrolling only happens in the element that the scrolling was
initiated in


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