289639 - Fixed-width text corrupted when scrolling down.

Status: RESOLVED EXPIRED

(Firefox :: General, defect)

Description

[Ian Brandt]

User-Agent:       Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-US; rv:1.7.6) Gecko/20050317 Firefox/1.0.2
Build Identifier: Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-US; rv:1.7.6) Gecko/20050317 Firefox/1.0.2

Fixed-width/teletype/monospaced text is corrupted at the bottom of the viewport
when scrolling down with the mouse.  It seems to happen when the scroll
intervals leave the text partially displayed at the bottom of the viewport
temporarily during the scroll process.  The display can be corrected when
scrolling up and down again so long as the text in question does not fall
partially on the bottom of the viewport again.  I only observe this with
fixed-width text.

Reproducible: Always

Steps to Reproduce:

Comment 1

[Ian Brandt]

Attachment: Screen shot demonstrating corrupted text.

Comment 2

[Ian Brandt]

Forgot to mention...  The bug occurs regardless of whether the Find Bar, Status
Bar, or a horizontal scroll bar is present at the bottom of the viewport.

Comment 3

[Ian Brandt]

I upgraded to 1.0.3 today and the problem appears to be gone.  It was always
reproducible before, and now I can't recreate it.  However, I upgraded to OS X
10.3.9 at the same time, and on account of the native scroll bars I'm guessing
Firefox uses some native widgets, so I'm not sure who to thank?

Comment 4

[Ian Brandt]

Okay, I lied, the bug still exists.  It's doesn't seem to happen as readily in
that not all the fyxed-width text that gets caught partially displayed at the
bottom of the viewport during scroll intervals is being corrupted, but it is
still happening.  Re-opening.

Comment 5

[Franck]

Hello,
I don't know if it depends but it sound like it.

Firefox 1.0.3, linux mandrake 9.2
My way on doing it appears:

First, it is not reproductible on every web page. It depends on
page content.
On bugzilla.mozilla.org, it won't appear ;-)

Go to any sourceforge project
http://sourceforge.net/tracker/?group_id=40604&atid=428519
Choose Bugs RFE or Lists page
-With DOWN ARROW key, scroll down, two keystrokes per second
until the line containing "Summary Admin Home Page Bugs.."
is under the naviguation tools bar.
-Hit 5 or 6 more times the down arrow key (scroll).
-Now press continuously UP ARROW  key

The line with "Summary Admin Home Page Bugs.." reappears
malformed.
But you can see on the same raster-line "Software/Group search"
without problem.
This eliminates a pure scrolling problem at window level.
-Now move mouse onto malformed links "Summary Admin ..."
They come back well redrawed !

It's like if the region for drawing the text is ok but the
the text is compressed.

-If you hit UP ARROW key  two keystroke/second, text is redrawn without problem.

Franck

Comment 6

[Tim Mann]

I have a really bad case of this with Firefox 1.0.2 (or Mozilla 1.7.6) on
Mandriva LE 2005 (= Mandrake 10.2).  I'm using a laptop with a 1400x1050
display, and the system thinks it's 99dpi.  The workaround of switching to 96dpi
(or 100dpi) does nothing for me.  Switching to different fixed width fonts
(Bitstream Vera Mono vs. Luxi Mono -- ugh) and different sizes (14 vs 15 pixels)
doesn't help.

I can easily reproduce it by scrolling around in this very bugzilla page. 
Getting a screenshot will be tricky, as the lines are instantly redrawn
correctly if I move my mouse pointer out of the window.

This bug (or something that looks just like it) has been happening on and off in
Netscape and Mozilla for years.  I recall first seeing it in Netscape for
Digital Unix on MIPS and/or Alpha boxes in the '90s.  I hadn't seen it for a
long time and blissfully assumed it was fixed.  For example, I didn't see it in
Mandrake 10.1 with the version of Mozilla that ships with that distro (sorry,
forgot what version that is).  It came back with a vengeance when I upgraded two
machines to LE 2005.

It's stunning that something this ugly can persist for so long.

Comment 7

[Gervase Markham [:gerv]]

This is an automated message, with ID "auto-resolve01".

This bug has had no comments for a long time. Statistically, we have found that
bug reports that have not been confirmed by a second user after three months are
highly unlikely to be the source of a fix to the code.

While your input is very important to us, our resources are limited and so we
are asking for your help in focussing our efforts. If you can still reproduce
this problem in the latest version of the product (see below for how to obtain a
copy) or, for feature requests, if it's not present in the latest version and
you still believe we should implement it, please visit the URL of this bug
(given at the top of this mail) and add a comment to that effect, giving more
reproduction information if you have it.

If it is not a problem any longer, you need take no action. If this bug is not
changed in any way in the next two weeks, it will be automatically resolved.
Thank you for your help in this matter.

The latest beta releases can be obtained from:
Firefox:     http://www.mozilla.org/projects/firefox/
Thunderbird: http://www.mozilla.org/products/thunderbird/releases/1.5beta1.html
Seamonkey:   http://www.mozilla.org/projects/seamonkey/

Comment 8

[Gervase Markham [:gerv]]

This bug has been automatically resolved after a period of inactivity (see above
comment). If anyone thinks this is incorrect, they should feel free to reopen it.