115232 - clicking on scroll bar can cause thumb to advance twice, overshooting the desired screen

Status: NEW

(Core :: XUL, defect)

Description

[iraqispy]

From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; SunOS sun4u; en-US; rv:0.9.6+) Gecko/20011213
BuildID:    2001121322

If I load a page more than two windows long, and click on the scroll bar to move
down by a screenful, Mozilla will occasionally page down twice.  If I double
click the scroll bar when the page is longer, it will usually page down three
times, sometimes four.

Reproducible: Sometimes
Steps to Reproduce:
1. Load any long page.
2. Click on the scroll bar well below the thumb (more than one thumb-length).
3. Or, double-click the scroll-bar more than two thumb-lengths below the thumb.

Actual Results:  Mozilla moves down more window-fuls than the number of times I
clicked.

Expected Results:  Mozilla should have moved down the number of window-fuls
corresponding to the number of times I clicked.

I'm running the Solaris2.6 12/13/01 nightly build, with tabs enabled.

Comment 1

[Sean Harding]

I've seen this as well. This problem has existed for a long time.

Comment 2

[Jim Crumley]

I can't seem to reproduce this with Sparc Solaris 7 build 2001121922.  Can you
reproduce this every time?

Comment 3

[Sean Harding]

The original description says "Reproducible: Sometimes."

That's my experience as well. Sometimes it works right, sometimes it doesn't.

Comment 4

[iraqispy]

The single-click behavior is only occasionally reproducible, but the double-click
behavior happens on any page over three screens long.  I'm using 2001122110
right now.  The page I'm currently viewing (bugzilla page for this bug) exhibits
the single-click behavior, but only (it seems) if I don't resize my window to
the point where a new line break is introduced.  Longer pages seem less likely
to cause the single-click behavior than ones which are about three screens long.
 I'll test more to see if it's really related to line-break/reflow.

Comment 5

[Jim Crumley]

I can confirm the double click behavior. I wonder if the double click is being 
interpreted as a long single click?  I also see movement of 5 screen-fulls when
triple clicking.

I can't confirm the single click behavior.  Even when setting the window size to
~ 3 screens for a given page, I still get only one screen-full of movement.

Comment 6

[Jim Crumley]

*** Bug 146419 has been marked as a duplicate of this bug. ***

Comment 7

[David Hyatt]

--> default owner

Comment 8

[Will Budreau]

Also seeing this in the auto-complete scroll bar, on Mac OS 10.1.5
BuildID: 2002081308

Type "bugz" into the address bar.
Click on the scroll bar on the auto-complete bar - if there's room, it'll hop
two screens.

Doesn't appear to happen on the URL given above.

Comment 9

[Greg K.]

See also bug 133110 and bug 144844, possible duplicates of this one (and which would make 
it All/All).

Comment 10

[Jean-Pierre Melkonian]

See my comment 9 on bug 144844

Comment 11

[Jean-Pierre Melkonian]

I have always the problem on Mac OSX.
and the summary should be:
"clicking on scroll bar cause always thumb to advance twice"
The scroll bar is unusable.
Actually i use
Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-US; rv:1.8a6) Gecko/20050111

My precedent comment was about MacOS9.

Comment 12

[Matthew Cline]

Still seeing this problem in the latest nightly builds of Minefiled on Linux.  Once when I clicked while my machine was doing some heavy swapping it went down *four* pages from a single click, so I'm wondering if this might be some problem with using different methods to determine the exact ime on the mouse down event and the mouse up event, thus leading to an incorrect computed duration for the mouse button being held down if the system is busy.