Open Bug 1672495 Opened 1 month ago Updated 24 days ago

Don't flash nested-subframe scrollbars on inital page reflow


(Core :: Panning and Zooming, defect, P3)





(Reporter: agi, Unassigned)


(Whiteboard: [geckoview])

Gecko flashes scrollbars on Android on page load which is a little bit jarring. It would be nice if we didn't.

Comparison with Chrome:

Whiteboard: [geckoview]

To be specific, there are scrollbars shown under 'ALL NEWS BOOKS' and under the day selector for the weather. There is also one shown for the root scroll frame.

(In reply to Agi Sferro | :agi | ⏰ PST | he/him from comment #0)

Comparison with Chrome:

The Chrome video also has scrollbars flashing, just for a very brief time.

My mistake, I was looking at the root scrollbar. This bug is about the subframe scrollbars.

Summary: Don't flash scrollbars on inital page reflow → Don't flash nested-subframe scrollbars on inital page reflow

The scrollbar is probably shown because we hit one of the ActivityOccurred() calls in nsGfxScrollFrame.cpp.
As a potential fix, we could skip the call for non-mIsRoot scroll frames when it is encountered for the first time. But this behavior should be controlled by a new LookAndFeel flag. We want to keep flashing subframe scrollbars on macOS.

Severity: -- → S3
Priority: -- → P3
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