19541 - [Dogfood] Browser jumps to top of page seconds after scrolling down

Status: VERIFIED FIXED

(Core :: XUL, defect, P1)

Description

[havoc]

Symptoms:
After scrolling down on a long page (e.g. www.freshmeat.net), the browser
jumps to the top of the page. The scrollbar remains in the position where
I left it, but scrolling again distorts the view.

To reproduce:
Go to a large page, scroll down using scrollbar or pgup/pgdn, release.
Move cursor over viewport. Watch the fireworks.

Version:
Nightly build, build 1999112108 for linux-i686-glibc.

Comment 1

[Peter Trudelle]

I don't see this, using 11/22 nightly build on RH Linux 6.0. resolving as
worksforme

Comment 2

[havoc]

I'm re-opening this bug, as I have reproduced it on several builds, even after
deleting ~/.mozilla. More details on this bug: This only happens when gfx
scrollbars are turned on. My system is Debian GNU/Linux Potato. This bug
makes browsing damn near impossible, I have turned gfx scrollbars of in the mean
time. Is this not reproducible on other Linux systems?

Comment 3

[Peter Trudelle]

That's a pretty crucial detail, although I have since seen this in one window
recently, without GFX scrollbars.  Couldn't reproduce it though.  reassigning to
evaughan as p1 for M12.  putting on dogfood radar.

Comment 4

[Richard Zach]

This happens invariably for me, on 1999112708 for Linux running on RH 6.0.
Works fine with gfx scrollbars off; with gfx scrollbars on, the browser jumps to
head of page as soon as I put pointer over a link (href or form button).  If I
then scroll upwards, the behavior is as one would expect if the page hadn't
jumped to the top.

Comment 5

[Syd Logan]

Ok, here is a foolproof easy way to cause this bug.
Start mozilla.
Then, let mozilla.org render.
Move the vertical scrollbar to the bottom of the page.
Now, move the mouse over into the mozilla.org page, being careful *not* to mouse
over any links. Move it around for a while, again avoiding links. Then, slowly
mouse over a link, and the page will jump. Seems like the bug has something to
do with the reflow that occurs in response to the mouseover. My senses tell me
that some variable or state that should be recorded by the gfx scrollbar when
the user moved the scrollbar to the bottom of the page is not being done, which
is what might be causing the reflow to render the page as though the scrollbar
were at 0, 0.

Added brendan to CC line per his request.,

Comment 6

[havoc]

The reflow Syd mentioned happens in the following situations:

1. Mousing over a link.
2. Activating a form control (e.g. click a button, text field).

Comment 7

[leger]

Putting on PDT+ radar.

Comment 8

[kinmoz]

I checked a fix for this into:

    mozilla/layout/html/base/src/nsScrollPortFrame.cpp revision 3.13

Modified nsScrollPortFrame::Reflow() to pass NS_FRAME_NO_MOVE_VIEW when
reflowing it's kidFrame.

r=[e-mail]

Fix should appear in the 12/01/99 Mozilla/SeaMonkey builds.

Comment 9

[Claudius Gayle]

VERIFIED with 1999120108 builds on all platforms. I wish everyone would
use the above format when marking a bug fixed.