235528 - Positioning of DIVs off bottom of screen is incorrect

Status: RESOLVED WORKSFORME

(Core :: Layout, defect)

Description

[Sean Ellis]

User-Agent:       
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.6) Gecko/20040206 Firefox/0.8

Follow the attached URL. The page consists of a main news area on the left, and
a navigation bar on the right. Scroll down. Text elements from the navigation
bar lose their horizontal positioning, and overwrite the text in the news area. 


Reproducible: Always
Steps to Reproduce:
1. Follow the attached URL (http://www.freedom-to-tinker.com/)
2. Scroll down

Actual Results:  
Navigation text elements rendered incorrectly over news stories.


Expected Results:  
Navigation elements should stay in the right hand portion of the screen.

Using DOM explorer suggests that the break between correctly and incorrectly
positioned navigation elements occurs within a single DIV section, which is odd.

It may be coincidence, but the problem occurs approximately at the bottom of the
visible screen - perhaps something to do with clipping? Resizing the browser
window, however, appears to have no effect.

I have seen this behavior in Mozilla 1.3a (yes, old I know), Firebird 0.6 and
Firefox 0.8.

Comment 1

[Hermann Schwab]

wfm Mozilla/5.0 (Windows; U; Win98; en-US; rv:1.6) Gecko/20040206 Firefox/0.8
wfm Mozilla/5.0 (Windows; U; Win98; en-US; rv:1.7a) Gecko/20040219

Screen resolution 800x600

Comment 2

[Sean Ellis]

Sorry, forgot to detail this originally - screen res 1280x1024 (x16 bits).

Comment 3

[Boris Zbarsky [:bzbarsky]]

Worksforme with a current trunk build as well.  Please test 1.7a....

Comment 4

[Sean Ellis]

Yes, confirmed same behavior with Mozilla 1.7a.

Comment 5

[Alex Hirzel]

WFM Mozilla/5.0 (Windows; U; Win98; en-US; rv:1.7a) Gecko/20040219

Tested 640x480, 800x600, 1024x768 (all at 24-bit color.)

Comment 6

[Sean Ellis]

I attempted to edit the referenced page into a minimal example of this problem. 

I notice that saving the page to a local disk, and then referencing the local
version, appears to clear up the problem.

This suggests to me that it may be something to do with progressive rendering. 

From a local file, all the information for the page is available in one go, so
the entire page layout is calculable before the page is first displayed. Across
a HTTP connection, the page is large enough that a display is requested before
download is complete.

I would suggest that the area off the bottom of the screen is probably created
in an interim form during the progressive rendering phase (with incomplete table
widths, etc), but that this information is not invalidated when the page is
complete. It therefore doesn't get updated correctly.

All of this IMO, of course. I may be wayyy off. But it "smells right" to me.

Comment 7

[Mats Palmgren (inactive)]

WFM 2004-08-20-07 trunk Windows XP.

Sean, do you still see the overlap with Mozilla 1.8a3 ?

Comment 8

[Mats Palmgren (inactive)]

WFM, 2004-09-11-07 trunk Linux.  Sean, feel free to reopen this bug if you
can reproduce the problem in a current nightly build:
http://ftp.mozilla.org/pub/mozilla.org/mozilla/nightly/latest/

-> WORKSFORME