[e10s][APZ] Scrollbar thumb doesn't redraw well if it was partially invisible before scrolling

NEW
Unassigned

Status

()

Core
Panning and Zooming
P3
normal
11 months ago
11 months ago

People

(Reporter: arni2033, Unassigned)

Tracking

53 Branch
Unspecified
Windows
Points:
---

Firefox Tracking Flags

(Not tracked)

Details

(Whiteboard: [gfx-noted])

Attachments

(1 attachment)

(Reporter)

Description

11 months ago
>>>   My Info:   Win7_64, Nightly 49, 32bit, ID 20160526082509
STR_1:
0.(unnecessary) Set "general.smoothScroll.mouseWheel.durationMaxMS" to 4000 to notice the bug better
1. Open http://www.kp.ru/daily/26592/3608653/
2. Scroll the left sidebar on the page to the bottom, so that only ~half of scrollbar thumb is visible
3. Hover mouse over the empty area in scrollbar (i.e. not scrollbuttons and not scrollbar thumb)
4. Rotate mouse wheel up once, wait until scrolling is finished
5. Repeat Step 4 several times

AR:
 Scrollbar thumb redraws with delays (Scrollbar smoothly moves to the top, and sometimes it appears
 clipped for ~0.5s. Then it redraws, and the whole visible area of scrollbar thumb is rendered fine.
 It is similar to page checkerboarding
ER:
 No glitches in scrollbar thumb
(Reporter)

Updated

11 months ago
Component: Untriaged → Panning and Zooming
Product: Firefox → Core
(Reporter)

Updated

11 months ago
No longer blocks: 1277113
OS: Unspecified → Windows
Priority: -- → P3
Whiteboard: [gfx-noted]
Version: Trunk → 53 Branch
I can repro minor checkerboarding and artifacts on the scrollbar. It looks like it is getting drawn as it scrolls into view, and there are lines on it dividing the old segment from the newly-drawn segment. The lines go away if I do something that causes the entire thumb to get redrawn.

No idea what's causing this. I'm not even sure if the scrollbar is a OS scrollbar or created by the page. I suspect the latter because of the auto-hiding behaviour it has but I can't find the element in the inspector.

Comment 2

11 months ago
Created attachment 8824754 [details]
testcase 1 - bug 1327932.zip

Attached testcase works better as a testcase, because it doesn't change length of the sidebar.

Comment 3

11 months ago
I'm not even seeing a scrollable sidebar on the page from comment 0 (nor on the page from comment 2, although I think that's not loading correctly to begin with due to character encoding issues).
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