Right widget sidebar in Edit Post flickers between two positions on scroll

[ericlewis]

See screenshare

[adamsilverstein]

Unfortunately, I was easily able to reproduce this bug in Chrome Beta/mac for a new post (in trunk): ​https://cl.ly/3s3G1T151d1o

[adamsilverstein]

In 37313.diff​ :

• Add a debouncedScrollHandler in editor-expand.js
• Use Underscore _.debounce in favor of setTimeout and afterScroll events

@ericlewis can you test this to see if it resolves the issue for you?

The flicker is caused by a secondary call to adjust in afterScroll. - the right bar gets pinned, then unpinned or the other way around, repeatedly.

My only concern here is that afterScroll was added to handle some edge case, maybe @azaozz
or @iseulde can tell us?

[desrosj]

This is still reproducible in Chrome 74.0.3729.169. 37313.diff​ no longer applies to trunk, though.

This seems relatively minor and does not affect the ability to accomplish and perform editing tasks. Since the Classic Editor is in a high priority/major bug fix and regressions only mode, I am going to close this one out.

That said, if someone feels passionately about fixing this, it wouldn't hurt to fix.