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Slight flicker in iOS Safari when cursor is placed past the first page of the document
Open, Needs TriagePublic

Description

Expected behavior

There shouldn't be any flicker when you place cursor anywhere in the document.

Actual Behavior

There is still a slight flicker whenever the cursor is placed anywhere past the first page of the document.

Configuration

Browser:
Device:

Event Timeline

Restricted Application added a subscriber: Aklapper. · View Herald TranscriptMay 24 2019, 10:21 PM

I have not yet been able to reproduce the issue first raised in T196839#5178009 and now represented by this ticket (T224322).

Attempt to reproduce iOS Safari flicker

YouTube: Mobile VE/iOS/Safari/Flicker: T224322

Configuration

Browser: Safari
Device: iPhone XS

Ryasmeen added a comment.EditedJun 13 2019, 10:40 PM

There is also an issue with cursor hiding behind the keyboard which happens if you just open link inspector and close it. You will loose the previous cursor position since the page abruptly scrolls down and will have to scroll down to find that position. I am noting it down here, incase these are relevant. if not, I will open a new ticket. Here is a screen capture showing that behavior:

Ryasmeen updated the task description. (Show Details)Jun 13 2019, 10:44 PM

@Ryasmeen this looks like a separate issue--could you make a separate task for it? Thank you!

marcella moved this task from To Triage to Revisit on the VisualEditor board.Jun 18 2019, 3:44 PM

@ppelberg This happens very inconsistently for me, like 1 in 20 tries or even less often. I was able to capture it after trying for some time:

Still frames from the video:

I am pretty sure that this weird flicker is caused by the code we added to fix T218414: Editing toolbar on mobile VE is not sticky (can scroll out of view) on iOS (where we essentially very quickly scroll down and then back up so that the toolbar position fixes itself). I noticed it back then, and noted it in a code comment in https://gerrit.wikimedia.org/r/c/mediawiki/extensions/VisualEditor/+/498256/3/modules/ve-mw/init/targets/ve.init.mw.MobileArticleTarget.js:

		// The scroll back up must be after a delay, otherwise no scrolling happens and the
		// viewports are not aligned. requestAnimationFrame() seems to minimize weird flashes
		// of white (although they still happen and I have no explanation for them).

As far as I can tell, there is no way to avoid this, as long as we require that workaround for the toolbar.