Post scheduler: Cannot move to prev/next month

[mmtr]

After upgrading to Gutenberg 6.3.0, I cannot move to the previous or next month when scheduling a post publish date. The date picker dialog is hidden after clicking on the navigation buttons:

The issue is not reproducible in Gutenberg 6.2.0.

[mmtr]

I wonder if this is a regression caused by #14851 cc @aduth

[youknowriad]

I think the problem is related to #14851 but the fix shouldn't be to update how withFocusOutside work. I think there's an a11y bug where in some browsers, the focus is lost entirely when we switch months. Ideally, when switching months, the focus should:

• Stay on the button we just clicked
• Focus the first day of the shown month.

[talldan]

Tricky one to resolve as the button is handled internally to https://github.com/airbnb/react-dates ... this component in particular:
https://github.com/airbnb/react-dates/blob/master/src/components/DayPickerSingleDateController.jsx

It seems like a completely new dom tree is mounted for the date picker on every month change, which seems entirely unnecessary. Initially I thought this key prop might be one of the reasons for that, but removing it has no effect on the bug:

gutenberg/packages/components/src/date-time/date.js

Line 67 in 2e45a8b

key={ `datepicker-controller-${ momentDate ? momentDate.format( 'MM-YYYY' ) : 'null' }` }

Did some digging in the issues and this seems like it might be relevant:
react-dates/react-dates#1006

[jorgefilipecosta]

I confirmed using git bisect that this regression was introduced in #14851.

[getdave]

Does this PR to the withFocusOutside HOC fix it?

#17051