1. Open the following URL: http://board.byuu.org/viewtopic.php?p=64035#p64035
2. Scroll all the way down
3. Start autoscrolling and try to scroll downwards
4. Try moving the mouse pointer around for a bit (but keep it below where you started autoscrolling, as if you're still trying to make the page go down more)
5. Alternatively enter Full Screen and watch how the page elements behave
In certain spots some of the page elements continuously start twitching up and down. I have attached screenshots showcasing the behavior.
Observed on lastest Nightly on Windows XP and Windows 7 64-bit.
Created attachment 623409 [details]
Created attachment 623410 [details]
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:15.0) Gecko/15.0 Firefox/15.0a1 ID:20120510021321
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:15.0) Gecko/15.0 Firefox/15.0a1 ID:20120510050721
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:15.0) Gecko/15.0 Firefox/15.0a1 ID:20120509222721
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:15.0) Gecko/15.0 Firefox/15.0a1 ID:20120509223521
Triggered by:Bug 681192
I can also reproduce on Linux
Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/15 Firefox/15.0a1 ID:20120512030520
screen capture http://youtu.be/YFSD3n3bYvk
Last good: c3d3bfb3b68d
First bad: 9d9a3edaa0b9
Created attachment 623625 [details] [diff] [review]
Created attachment 623639 [details] [diff] [review]
Comment on attachment 623639 [details] [diff] [review]
>+ virtual void ScrollToCSSPixels(nsIntPoint aScrollPosition) = 0;
Please add to the doc comment that the scroll mode is INSTANT.
Shouldn't nsScrollBoxObject::ScrollTo change in same way?
Yes, I'll do that separately.
Created attachment 623885 [details] [diff] [review]
Comment on attachment 623885 [details] [diff] [review]
Fx 15.0a1 2012-05-19
I can still reproduce parts of this, although it is fixed for autoscrolling.
Using the same URL, or one of quite a few others (http://www.less-broken.com/blog/2012/05/no-www-considered-harmful.html is one example), I can reproduce twitchy elements using the following steps:
1. Scroll to the bottom of the page with the mouse wheel.
2. Scroll down some more with the mouse wheel.
(Alternative to step 2 is scroll left with a tilt-wheel, if you have one).
This doesn't happen every time, but fairly often.
(I have no idea why the blocker got removed, thanks Ryan).
Confirmed with STR(Alternative to step 2 is scroll left) of comment #17 in
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:15.0) Gecko/15.0 Firefox/15.0a1 ID:20120519030527
Created attachment 625905 [details] [diff] [review]