382961 - Repeated lines (border style?) when using arrow keys or the scroll bar to navigate

Status: RESOLVED WORKSFORME

(Core :: Layout, defect)

Description

[Reece H. Dunn]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9a4) Gecko/20070427 GranParadiso/3.0a4
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9a4) Gecko/20070427 GranParadiso/3.0a4

When you use the down arrow key to scroll the document given in the URL above, the code fragments (which has a border-top style specified) get rendered with the border repeated at every key down scroll interval (that is, the distance scrolled as a result of pressing the down arrow key).

The same thing happens with the scroll bar.

Reproducible: Always

Steps to Reproduce:
1. Go to http://www.codeproject.com/cpp/TravellingSalesman.asp
2. Press the page down key until you reach the bottom of the document, pausing briefly after each press
3. Press the page up key until you reach the top of the document, pausing briefly after each press
4. Press and hold the down arrow key until you reach the bottom of the document
5. Press and hold the up arrow key until you reach the top of the document
6. Press the mouse button on the scroll bar slider and slowly scroll to the bottom of the document
7. Press the mouse button on the scroll bar slider and slowly scroll to the top of the document
8. Press and hold the down scroll arrow on the scroll bar until you reach the bottom of the document
9. Press and hold the up scroll arrow on the scroll bar until you reach the top of the document

Actual Results:  
When scrolling down, in all cases (not as noticeable using the page down key, but still evident), when moving over the "Algorithm" and "code segment:" code listings, the black line at the top of the code block gets repeated throughout that HTML element.

When scrolling up, the same thing happens, but with a white line.

Expected Results:  
In all cases, the document should be rendered correctly during the scrolling if you pause part way through the scrolling process.

I have experienced something similar when composing e-mails with hotmail.

I suspect that this is in the rendering of the CSS border style. When scrolling, I suspect that the position of the element containing that style is not correctly updated with respect to the windows viewport.

Comment 1

[Ria Klaassen (not reading all bugmail)]

These specific lines are a regression from bug 177805 (some lines seem to have different regression dates). 

Comment 2

[Eli Friedman]

Screnshot?  I'm not really sure what the issue is.

Comment 3

[Ria Klaassen (not reading all bugmail)]

Attachment: screenshot lines

The lines are easier to reproduce by scrolling up with the mouse.

Comment 4

[Ria Klaassen (not reading all bugmail)]

With the mouse wheel, sorry. When you touch the scroll bar, they disappear.

Comment 5

[Eli Friedman]

Must be DPI dependent or something; I can't reproduce.

Comment 6

[Ria Klaassen (not reading all bugmail)]

Even more lines with smooth scrolling on. 96 dpi here.

Comment 7

[Ria Klaassen (not reading all bugmail)]

Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9a5pre) Gecko/20070516 Minefield/3.0a5pre
This is weird; I tried another computer, a much faster one but this one has even more trouble and it also shows white lines, even with the scroll bar and also when scrolling down.

Comment 8

[Ria Klaassen (not reading all bugmail)]

Attachment: White lines on Vista when scrolling back

Comment 9

[Martijn Wargers (dead)]

I think related to bug 373079, that bug has a testcase.

Comment 10

[Martijn Wargers (dead)]

Can this bug still be reproduced with current trunk build?
I can't seem to reproduce anymore.

Comment 11

[Léon Swinkels]

Attachment: Screenshot of website with scrolling lines

This picture shows a page with the scrolling lines visible.
This happens only when you are zoomed in. (verified)

Comment 12

[Martijn Wargers (dead)]

That's this site:
https://www.sdn.sap.com/irj/sdn/weblogs?blog=/pub/wlg/1948
That is also worksforme in current trunk build on windowsXP.

Comment 13

[Martijn Wargers (dead)]

Leon, can you reproduce it with https://bugzilla.mozilla.org/attachment.cgi?id=257739 (testcase from bug 373079)?

Comment 14

[Ria Klaassen (not reading all bugmail)]

I can't reproduce this anymore with latest trunk on WinXP.

Comment 15

[Martijn Wargers (dead)]

I saw it once after a lot of zooming in and out with a testcase and then scrolling, but I couldn't reproduce it afterwards anymore.

Comment 16

[Daniel.S]

I can't reproduce any of the cases mentioned here.
Some of the line regressions have been fixed not long before Fx3, but I never encounteres them in release builds (or current trunk).