285004 - Horizontal lines in iframes and across images when scrolling

Status: RESOLVED WORKSFORME

(Core :: Layout, defect)

Description

[Peter Weilbacher]

I see horizontal (dark) lines across some iframes and images in several
webpages, most notably on the current OS/2 trunk builds but also on current
Linux GTK1 trunk builds. The three iframes in the example URL
<http://tinderbox.mozilla.org/showbuilds.cgi?tree=SeaMonkey> show this behavior
on both OS/2 and Linux when I scroll the whole page so that these iframes appear
or disappear from the content area.

I originally wanted to post this to bug 201198, but the horizontal lines that
Hartmut and me see are dark and not white. Also that bug has various reports
that to me already seem like a mix of different bugs. With my profile on the
current OS/2 trunk I can see the dark stripes in Hartmut Krafft's examples (only
on OS/2) but I do not see them in the original example of bug 210198 nor in the
ones that Jon Barber or oliv posted in the same bug.

Interesting is also that a fresh profile does not have any of these problems,
but I didn't manage to find out which preference was responsible (it is none of
the obvious ones like smooth scrolling or graphics resizing).

(I looked for quite some time for a dupe but didn't really find the same behavior.)

Comment 1

[R.K.Aa.]

Edit->Preferances->Appearance->Fonts:

Is "Display resolution:" set to the same in the profile that works and one that
doesn't? 

Comment 2

[Peter Weilbacher]

Yes, set to "System setting" in both.

Comment 3

[R.K.Aa.]

bug 201198 / bug 111176 are likely two versions of the same bug..

Comment 4

[Peter Weilbacher]

OK, for the iframe part of this, bug 111176 might be a dupe. Then the remaining
image part seems to be OS/2 specific. Was probably stupid of me to file this in
one bug it just looks so similar...

Comment 5

[Jasper Lieber]

>  ------- Additional Comment #3 From R.K.Aa.  2005-03-06 10:24 PST   -------
> bug 201198 / bug 111176 are likely two versions of the same bug..

I would support that, although the 2nd title is better!
 Bug 111176  Mysterious black lines appear when scrolling the window
 Bug 285004  Horizontal lines in iframes and across images when scrolling

Comment 6

[Jasper Lieber]

> ------- Additional Comment #3 From R.K.Aa.  2005-03-06 10:24 PST   -------
> bug 201198 / bug 111176 are likely two versions of the same bug..

Wait, I was mistaken in my last post.  Here's what I think:

Here are the relevant bugs
  Bug 111176  Mysterious black lines appear when scrolling the window
has references to a number of bugs, including:  
  Bug 201198  White lines appear on images when scrolling slowly through page
  Bug 284986  Bad rendering of gif images with transparency (banding, stripes)
when slow scrolling on/off a pane
  Bug 285004  Horizontal lines in iframes and across images when scrolling

I believe the chat at bug 201198 has been about several bugs, and that bug
284986 is a specific example.  I believe that 285004 is another example of
201198.  I also think 111176 and 285004 are dupes (though 285004 has a better
title!).

Comment 7

[Hartmut Krafft]

To confuse things a little bit more:

I don't see *dark* lines when scrolling over images, but lines in the webpage's
background colour. Usually, white lines. 
See 
attachment #176247 [details] 
attachment #176379 [details] 
attachment #176381 [details]

Didn't notice the iframe problem, till now.
I didn't change the profile, will have to test on another box.

One thing I can say for sure: the problem is absent in
Mozilla/5.0 (OS/2; U; Warp 4; en-US; rv:1.7.3) Gecko/20040918

and present in 1.8b2.

Hartmut

Comment 8

[Peter Weilbacher]

OK, I found the preference that causes the dark lines on the tinderbox page. It is
user_pref("font.size.variable.x-western", 13);
or Edit -> Preferences -> Appearance -> Fonts -> Proportional Size. Any other
odd size >12 also causes stripes in the three iframes when scrolling while even
sizes work fine. This was on OS/2, will try on Linux GTK1 later.

Setting an even font size also seems to "fix" the problem on Hartmut's example
page <http://www.wetter-zentrale.com/topkarten/tkavnmgeur.htm>.

Btw, this is different from bug 111176 then, with even font sizes I continue to
see the black lines on the collapsed border example there.

Comment 9

[Peter Weilbacher]

OK, the tinderbox iframes show exactly the same behavior on Linux trunk (GTK1),
while the weather graph never shows lines.

Comment 10

[Peter Weilbacher]

Attachment: minimal testcase for iframe case

The minimal useful testcase for the case of stripes in the iframe. float can be
either left or right but not none, I tried different values of margin-top but
only 0.5em shows the stripes. The font size in preferences has to be set to an
odd number >12 (i.e. 13, 15, 17).

Comment 11

[Peter Weilbacher]

Attachment: screenshot of testcase

This shows the iframe problem with the minimal testcase with
Mozilla/5.0 (OS/2; U; Warp 4.5; en-US; rv:1.8b2) Gecko/20050313
The stripes only happen when scrolling upwards, they are densest when moving
the scrollbar handle, while they are larger using the scrollmouse. I guess
every time the content area is refreshed, one line gets added.

Comment 12

[Peter Weilbacher]

Hmm, can anybody else reproduce on Linux? I do see it with my normal GTK1 build
on my work machine (RedHat 7.3 based) with
   Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8b2) Gecko/20050314
but not on a Fedora Core 1 based laptop, even if using the same Mozilla
binaries. Can this be a bug in the XFree version or driver? If so, I tend to
mark this bug OS/2 only.

Comment 13

[Peter Weilbacher]

Marking OS/2 only and confirming, several people from the newsgroup have
reproduced this using OS/2.

Comment 14

[Peter Weilbacher]

Oh, I changed from All to OS/2 because I tried the same GTK1 build on several
Linux machines now and can really only reproduce this on one of them (which
sometimes acts weird in other respects as well).

Comment 15

[Peter Weilbacher]

Hmm, tried again just now with 
Mozilla/5.0 (OS/2; U; Warp 4.5; en-US; rv:1.8b4) Gecko/20050726 SeaMonkey/1.0a
and I don't get stripes any more, neither on the tinderbox page, nor the
testcase attachment, nor with Hartmut's wetter-zentrale example. And in
spiegel.de images I haven't seen this either in the last few weeks.

If there are no other observations I will mark this one WORKSFORME soon.