Closed Bug 1455285 Opened 2 years ago Closed 2 years ago

Blank space shows at the the bottom while dynamic toolbar is partially onscreen


(Firefox for Android :: Toolbar, defect, P1)

Firefox 61



Firefox 61
Tracking Status
firefox59 --- unaffected
firefox60 --- unaffected
firefox61 + fixed


(Reporter: kats, Assigned: botond)



(Keywords: regression)


(1 file, 1 obsolete file)

For the last week or so I've been seeing blank white space at the bottom of the screen when the dynamic toolbar is partially visible. The size of the blank space corresponds to the amount of the toolbar that is visible.

Fennec Nightly, on a Sony Xperia XZ1 with Android 8.0

- Go to
- Zoom in a bit
- Scroll up and down
I wasn't able to reproduce on my HTC M8 w/ Android 7.1, FWIW.
I bisected using mozregression, it gave me this:

Not what I would have guessed, but I guess not totally implausible? I verified the last good/first bad again to make sure.

The change does touch some stuff in AsyncCompositionManager.cpp which might have caused this.
Blocks: 1420512
Has Regression Range: --- → yes
Has STR: --- → yes
OS: Unspecified → Android
Hardware: Unspecified → All
Version: 57 Branch → Firefox 61
Attached patch Potential fix (obsolete) — Splinter Review
Apologies for the additional regression from bug 1420512.

I don't have an Android build to test this with right now, but the attached patch might fix the problem.
(After catching a similar regression during the review of bug 1454485, I audited uses of ScrollbarData::mDirection to make sure that they reflect the fact that it's now set for both thumb and scrollbar container layers, but I missed the Android-only uses...)
Assignee: nobody → botond
Priority: -- → P1
Comment on attachment 8969398 [details] [diff] [review]
Potential fix

Review of attachment 8969398 [details] [diff] [review]:

Yup, the try push with this fix doesn't have the issue. Thanks!
Attachment #8969398 - Flags: review+
Great, thanks for testing!
Comment on attachment 8969687 [details]
Bug 1455285 - In MoveScrollbarForLayerMargin(), move the actual scrollbar thumb layer, not the scrollbar container layer.
Attachment #8969687 - Flags: review?(bugmail) → review+
Attachment #8969398 - Attachment is obsolete: true
Pushed by
In MoveScrollbarForLayerMargin(), move the actual scrollbar thumb layer, not the scrollbar container layer. r=kats
Closed: 2 years ago
Resolution: --- → FIXED
Target Milestone: --- → Firefox 61
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