Alice0775 White Reporter
	Description • 14 years ago

Build Identifier:
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b11pre) Gecko/20110127 Firefox/4.0b11pre ID:20110127030333

Synchronization with the turn of a mouse wheel is lost when mouse pointer hover over buttons. And scroll width decreases.

This is the factor that scroll with the mouse wheel becomes slow.

Reproducible: Always

Steps to Reproduce:
1. Start Minefield with new profile and install much add-ons
2. Enable Smooth Scroll
3. Open Addons Manager (Ctrl+Shift+A) and Select Extensions pane

4. Put a mouse pointer on a button
5. Scroll by mouse wheel one tick

Try to compare it with the following
6. put a mouse pointer on a addon's icon
7. Scroll by mouse wheel one tick

Actual Results:
 Synchronization with the turn of a mouse wheel is lost when mouse pointer hover over buttons. And scroll width decreases

Expected Results:
 It should be scrolled in the same speed

	Timothy Nikkel (:tnikkel) Assignee
	Comment 1 • 14 years ago

Seems about the same for me on my Linux machine.

	Alice0775 White Reporter
	Comment 2 • 14 years ago

(In reply to comment #1)
> Seems about the same for me on my Linux machine.

Yes, It does not happen on Linux build.

It happens on Windows build only.

	Timothy Nikkel (:tnikkel) Assignee
	Comment 3 • 14 years ago

I wonder if this is a regression or not.

	Alice0775 White Reporter
	Comment 4 • 14 years ago

WORKAROUND: append the following CSS to userContent.css

.addon-control {
  box-shadow: none !important;
}

	Alice0775 White Reporter
	Comment 5 • 14 years ago

Try wheel scroll
you should enable smooth scoll

Left side box : wheel scroll is lagged
Right side box: wheel scroll is normal

	Alice0775 White Reporter
	Comment 6 • 14 years ago

The problem in comment #5 also happens on Linux.

	Timothy Nikkel (:tnikkel) Assignee
	Comment 7 • 14 years ago

Wow, thats a great test case Alice. I can see the difference on Linux. Has that testcase always acted like that or did it regress sometime I wonder.

	Alice0775 White Reporter
	Comment 8 • 14 years ago

Regression window for attachment 509754 [details](cached m-c hourly):
Works:
http://hg.mozilla.org/mozilla-central/rev/aefb8c332502
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b6pre) Gecko/20100910 Firefox/4.0b6pre ID:20100911084458
Fails:
http://hg.mozilla.org/mozilla-central/rev/26bfc0860822
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b6pre) Gecko/20100910 Firefox/4.0b6pre ID:20100911102300
Pushlog:
http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=aefb8c332502&tochange=26bfc0860822
Candidate:
Bug 590039 - fix blur radius computation and rename -moz-box-shadow to box-shadow

	Timothy Nikkel (:tnikkel) Assignee
	Comment 9 • 14 years ago

That's because "box-shadow" will have no effect prior to that change set because it wasn't recognized; only the the prefixed version -moz-box-shadow was recognized.

	Alice0775 White Reporter
	Comment 10 • 14 years ago

Regression window(cached m-c hourly):
Works:
http://hg.mozilla.org/mozilla-central/rev/b94cf8147ccd
Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.3a1pre) Gecko/20100111 Minefield/3.7a1pre ID:20100111140136
Fails:
http://hg.mozilla.org/mozilla-central/rev/47cd92d616d7
Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.3a1pre) Gecko/20100111 Minefield/3.7a1pre ID:20100111150802
Pushlog:
http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=b94cf8147ccd&tochange=47cd92d616d7
Candidate;
Bug 526394 - Move scrolling out of the view system into layout

	Timothy Nikkel (:tnikkel) Assignee
	Comment 11 • 14 years ago

Interesting, thank you very much Alice.

	Timothy Nikkel (:tnikkel) Assignee
	Comment 12 • 14 years ago

This might be the explanation for the mysterious scrolling bugs (slow scrolling, laggy scrolling, jerky scrolling, amount of scrolling decreased) we have been seeing.

	Timothy Nikkel (:tnikkel) Assignee
	Comment 13 • 14 years ago

The first bad revision is:
changeset:   37083:4ccff5df452c
user:        Robert O'Callahan <robert@ocallahan.org>
date:        Thu Oct 08 16:01:15 2009 +1300
summary:     Bug 526394. Part 31: Move scroll implementation into nsGfxScrollFrame. r=mats

	Timothy Nikkel (:tnikkel) Assignee
	Comment 14 • 14 years ago

smooth scroll just makes this more obvious, it happens without it.

	Timothy Nikkel (:tnikkel) Assignee
	Comment 15 • 14 years ago

We reflow while smooth scrolling and nsGfxScrollFrameInner::CurPosAttributeChanged gets called from the scroll frames ReflowFinished reflow callback. It gets the position information from the scrollbar and then calls ScrollTo(dest, INSTANT) because the scrollbar does not have the smooth attribute (it didn't on 3.6 either). That cancels the inprogress async smooth scroll. dest is actually the current position of the scroll frame anyway, so the scroll call is useless, but it only determines that after cancelling the async scroll. http://hg.mozilla.org/mozilla-central/rev/4ccff5df452c removed a "if (x == curPosX && y == curPosY) return;" check in nsGfxScrollFrameInner::CurPosAttributeChanged. I think we should just restore it.

This patch also improves the behaviour when I scroll down quickly with the mouse wheel and smooth scrolling is turned off.

	Timothy Nikkel (:tnikkel) Assignee
	Comment 16 • 14 years ago

The reason that non-smooth scrolling is improved is that we still use an async scroll with a timer to do the scrolling, so if we get a couple of nsGfxScrollFrameInner::ScrollTo calls without the async timer happening and then a reflow (off the refresh driver or will paint) it will end up in nsGfxScrollFrameInner::CurPosAttributeChanged and try to scroll INSTANT to the current position even though there is an async scroll object pending for many pixels further down.

The following dump makes it plain.

nsGfxScrollFrameInner::ReflowFinished calling CurPosAttributeChanged
I'm nsGfxScrollFrameInner::CurPosAttributeChanged and i'm calling ScrollTo
nsGfxScrollFrameInner::ScrollTo aScrollPosition 0 0 (0 0) mode INSTANT
nsGfxScrollFrameInner::ScrollTo aScrollPosition 0 51 (0 3060) mode SMOOTH
nsGfxScrollFrameInner::AsyncScrollCallback calling ScrollToImpl with dest 0 51 (0 3060)
nsGfxScrollFrameInner::ScrollTo aScrollPosition 0 102 (0 6120) mode SMOOTH
nsGfxScrollFrameInner::ScrollTo aScrollPosition 0 153 (0 9180) mode SMOOTH
nsGfxScrollFrameInner::ScrollTo aScrollPosition 0 204 (0 12240) mode SMOOTH
nsGfxScrollFrameInner::ScrollTo aScrollPosition 0 255 (0 15300) mode SMOOTH
nsGfxScrollFrameInner::ReflowFinished calling CurPosAttributeChanged
I'm nsGfxScrollFrameInner::CurPosAttributeChanged and i'm calling ScrollTo
nsGfxScrollFrameInner::ScrollTo aScrollPosition 0 51 (0 3060) mode INSTANT
nsGfxScrollFrameInner::ScrollTo aScrollPosition 0 102 (0 6120) mode SMOOTH
nsGfxScrollFrameInner::AsyncScrollCallback calling ScrollToImpl with dest 0 102 (0 6120)

	Robert O'Callahan (:roc) (email my personal email if necessary)
	Comment 17 • 14 years ago

Right. OK. Great!

	Timothy Nikkel (:tnikkel) Assignee
	Comment 18 • 14 years ago

http://hg.mozilla.org/mozilla-central/rev/2ba4709dc2ce

	Robert O'Callahan (:roc) (email my personal email if necessary)
	Comment 19 • 13 years ago

I don't think anything still needs landing here.