758967 - Disable smooth scrolling by default (at least on Windows XP)

Status: RESOLVED WONTFIX

(Core :: Web Painting, defect)

Description

[Marco Castelluccio [:marco]]

Smooth scrolling has been enabled by default in bug 198964, but I think the feature isn't ready to be enabled by default on every machine.

I've tried on two different Windows XP machines, and there is a huge rendering problem related to the screen refresh.

Can't we disable this feature by default, at least on Windows XP?
And maybe re-enable it when bug 689418 (or other bugs blocking bug 710372) lands?

Comment 1

[Avi Halachmi (:avih)]

Can you please describe the issue in details, beyond "there is a huge rendering problem related to the screen refresh"?

Comment 2

[Marco Castelluccio [:marco]]

I mean screen tearing. The recent refresh driver related patches could have solved this problem (I'll test as soon as possible), but not for Firefox 13.

Comment 3

[Timothy Nikkel (:tnikkel)]

Is it the same in nightly? We've had some patches land that fix screen tearing issues, not sure which versions they correspond to (or have the bug numbers handy).

Comment 4

[Marco Castelluccio [:marco]]

(In reply to Timothy Nikkel (:tn) from comment #3)
> Is it the same in nightly? We've had some patches land that fix screen
> tearing issues, not sure which versions they correspond to (or have the bug
> numbers handy).

As I said in comment 2, I don't know yet. I'll test as soon as possible (the two Windows XP machines aren't mine).
However for Firefox 13 the problem is still there and the patches won't be backported, so probably we should disable smooth scrolling, at least on Windows XP (if this problem is widespread).

P.S.: Forgot to mention the two machines have layers acceleration blocked because of old NVIDIA drivers.

Comment 5

[Jared Wein [:jaws] (please needinfo? me)]

I'd just be worried about disabling the feature for all WinXP users when this seems to be the first bug of the Aurora & Beta cycle I've seen that brings complaints specific to XP on Fx13.

Comment 6

[Avi Halachmi (:avih)]

If you're really speaking of tearing (as defined here: http://en.wikipedia.org/wiki/Screen_tearing ), then I'd say it should probably be WONTFIX. Tearing on XP depends on many things, and for the most part, the OS itself has tearing everywhere (even when dragging a window around). That's the nature of a non-comosited desktop in general, and of XP specifically.

If anyone's interested, here's a page explaining the issue which I wrote for SmoothWheel, and a link at the bottom which _might_ work around desktop vsync in XP: http://smoothwheel.mozdev.org/smoother_smoothwheel.php

Overall, IMO, the advantages of smooth scrolling far outweigh the slightly suboptimal scroll caused by tearing.

Comment 7

[Marco Castelluccio [:marco]]

(In reply to Avi Halachmi (:avih) from comment #6)
> If you're really speaking of tearing (as defined here:
> http://en.wikipedia.org/wiki/Screen_tearing ), then I'd say it should
> probably be WONTFIX.

Yes, I'm speaking of tearing.

> Overall, IMO, the advantages of smooth scrolling far outweigh the slightly
> suboptimal scroll caused by tearing.

On the two PCs I've tested, smooth scrolling wasn't just slightly suboptimal, tearing was really a lot visible. I couldn't read while scrolling. (And the tearing was only visible while scrolling in Firefox, not while dragging windows or during other XP animations)

(In reply to Jared Wein [:jaws] from comment #5)
> I'd just be worried about disabling the feature for all WinXP users when
> this seems to be the first bug of the Aurora & Beta cycle I've seen that
> brings complaints specific to XP on Fx13.

Yes, my advice was to disable this by default if the problem is widespread. I've only checked on two different machines.

Comment 8

[Marco Castelluccio [:marco]]

I guess this isn't going to happen.