246394 - Page flashing with JS style.display "block" and "none"

Status: RESOLVED DUPLICATE of bug 132337

(SeaMonkey :: General, defect)

Description

[travis]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.6) Gecko/20040206 CombustionTiger/0.8 (All your Firefox/0.8 are belong to Firesomething) TraviBlog: http://travis.servebeer.com/blog.net/
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.6) Gecko/20040206 CombustionTiger/0.8 (All your Firefox/0.8 are belong to Firesomething) TraviBlog: http://travis.servebeer.com/blog.net/

(from http://forums.mozillazine.org/viewtopic.php?t=83899)

If you visit this page and click on the imagemap links you'll see what I mean:
http://www.brandensemble.com/features2.html
it appears to be valid :
http://validator.w3.org/check?verbose=1&uri=http%3A//www.brandensemble.com/features2.html

I can produce it in:
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.6) Gecko/20040206 Firefox/0.8
Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.7) Gecko/20040608
Firefox/0.8.0+
Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.6) Gecko/20040113
Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.4) Gecko/20030624
Netscape/7.1 (ax)

If I set the <div> which contains the imagemap to position:absolute the flashing
doesn't occur, but I really wouldn't like to go that route.

Here's the JS I'm using to show/hide the <div>s:
[code]
var ie = document.all ? 1 : 0;
var ns = document.layers ? 1 : 0;
var dom = document.getElementById ? 1 : 0;
var activePop = 0;
function showPopup(idNum)
{
	if (dom)
	{
		if (activePop > 0)
		{
			document.getElementById("popup" + activePop.toString()).style.display="none";
			document.getElementById("popupro" + activePop.toString()).style.display="none";
		}
		document.getElementById("popup" + idNum.toString()).style.display="block";
		document.getElementById("popupro" + idNum.toString()).style.display="block";
		activePop = idNum;
	}
}
[/code]

...and...

[code]
 href="#" onclick="javascript:showPopup(1); return false;" 
[/code]

it doesn't occur in IE5/IE6/Safari/Opera 7.51

Reproducible: Always
Steps to Reproduce:
1. create page with several <div>s in a row
2. change <div>#2.style.display from "none" to "block" (or vice versa)
3. observe brief flicker

Actual Results:  
The second <div> jumps up to the top of the page briefly enough to cause a
slight flicker

Expected Results:  
there should be no flicker

I've never noticed this before, and it has been difficult for me to reproduce. 
The xHTML and CSS are both valid.

Comment 1

[Martijn Wargers (dead)]

probably related to bug 246138, but this bug needs a minimal testcase.

Comment 2

[travis]

Attachment: Mozilla bug #246394 display:block flicker simplified test

this is a simplified test page which will show a flicker even when an elements
style.display is toggled between 'block' and 'none'.  the element that flickers
has the float set to 'left' or 'right' and the overflow is set to 'auto' or
'scroll'.  Test cases and workaround included in source.

Comment 3

[Erik Fabert]

A float & overflow:auto & display toggles between "block" and "none", sounds 
familar...

*** This bug has been marked as a duplicate of 132337 ***