275616 - moving the mouse over a bunch of 'mouseover' links causes flashes

Status: RESOLVED INVALID

(Core Graveyard :: GFX: Win32, defect)

Description

[Rob Yampolsky]

When I move the mouse around a web page with a lot of links set to change color
when the mouse moves over them, white horizontal lines flash across the window.

Similar flashes occur during repaints as pages load and reformat themselves with
new info.

I assume this has something to do with updating the window out of sync with the
monitor.  But what strikes me as really strange is that sometimes the flashes
extend beyond the Firefox window.

Is this a bug, or is Firefox somehow bypassing the normal window painting (for
speed?) and forcing painting to occur out of sync with monitor refresing?

By the way, I tried to duplicate this in IE (I'm on Win2000).  It sometimes
happens there too, but not as severely, and I don't think it extends outside the
window.

Comment 1

[Boris Zbarsky [:bzbarsky]]

Sounds like a buggy graphics card driver, actually.... Rob, can you point to an
example page showing the problem?

Comment 2

[Rob Yampolsky]

You may be right about it's being a buggy graphics card (or Windows driver).

It happens really obviously at www.zdnet.com.  They have a dark blue background,
so it's really easy to see the white horizontal lines that flash as you move the
mouse over a group of mouse-over highlighted links.

This happens in IE as well, but it's not quite as bad there.  Not sure why, but
if it's a driver bug, probably not worth worrying about.

F.Y.I. - my machine has an S3 Savage4 card.  Windows 2K reports the driver
version as 5.01.840.0001.

Comment 3

[Boris Zbarsky [:bzbarsky]]

Yeah, that definitely sounds like a bug in the driver, if it's a problem for all
apps.

Could you possibly install whatever the most recent driver for that card is and
test with that?

Comment 4

[Rob Yampolsky]

I just noticed that this happens whether or not the link in question has any
mouseover effects.

It's enough to move the mouse over a list of links to make it happen.  For
example, the 'Recent Software' section on the upper right side of dot.kde.org. 
Also noticed it today just moving the mouse over a set of images on ophoto.com.

I think it has something to do with the link URL's being displayed on the status
bar.  Could Firefox be repainting the whole window whenever it updates the
status bar.  In other words, could this be a graphics card problem that's being
worsened by extra screen paints.

Comment 5

[Boris Zbarsky [:bzbarsky]]

No, changing the status bar text should just repaint the status bar...

Comment 6

[Rob Yampolsky]

I guess the operative word here is 'should'.  The fact remains that something's
happening video-wise when I move the mouse around these pages, and since the
links are not being highlighted, and the only thing I see changing in the FF
window is the status bar, I can't think of any other cause than the URL status
display triggering a repaint of the whole window.

Previously, I reported that the same problem happens on IE, which reinforced the
'bad video driver' theory.  True, when links are set for mouseover highlighting
(as on zdnet), I see the flashes in IE too.  But on dot.kde.org, it does not
happen on IE.

Could this be theme-related?  Do themes have any influence on how and when
things are painted in FF?  I'm using Plastikfox Nuvella.

Comment 7

[Boris Zbarsky [:bzbarsky]]

Yes, different themes would absolutely lead to different areas being repainted,
and a silly-enough theme would cause the whole window to repaint.

Comment 8

[Rob Yampolsky]

Well, that seems to be it.  I switched to the default theme, and the problem has
gone away.  Doesn't happen at all on dot.kde.org.  Still happens on zdnet.com,
but there you have mouseover repainting.  Also, it happens less now (maybe even
less than with IE).

Thanks for your input.  I'm going to pass this on to the plastikfox theme developer.

Comment 9

[Boris Zbarsky [:bzbarsky]]

OK.  Marking invalid, since it's an interaction between theme and graphics
drivers here....