Force popover contents to stay in the same position side once open

[chandlerprall]

Closes #1187

Summary

Previously, a popover could jump to a different position (top, left, right, bottom) when its contents changed or onScroll (if the repositionOnScroll prop was passed). This PR changes the behaviour to lock the popover to whatever position it initially opens to, unless the window is resized.

While it is locked to a side, the popover still re-positions to center content, keep the correct offset, and other position calculations - but it only calculates those for the now-forced position.

This is testable by editing the popover's DOM content in chrome dev tools.

Checklist

• This was checked in mobile
• This was checked in IE11
• This was checked in dark mode
• Any props added have proper autodocs
• Documentation examples were added
• A changelog entry exists and is marked appropriately
• This was checked for breaking changes and labeled appropriately
• Jest tests were updated or added to match the most common scenarios
• This was checked against keyboard-only and screenreader scenarios

[cjcenizal]

It looks like this is partially working, but there's an odd bug I encountered when I tested it in Kibana:

This popover is positioned with downRight. When I first enter input into the search, the popover repositions which is unexpected. But the good thing is that it doesn't reposition after that.

[chandlerprall]

@cchaos please test again with the context menu stuff, should be positioning correctly now

@cjcenizal should have your 2nd case (jumping on first input) fixed now

[cjcenizal]

Nice work! Tested this locally and it looks like it's working.

Code LGTM.

[cchaos]

It's working very well, there are some edge cases when the trigger is near browser edges, but I think those can be fixed in implementations and don't need to be handled here.

Is there any way to possibly not visibly show the popover/context menu until it is in the new position?

There's a flash of it in the wanted position until it re-positions.

[chandlerprall]

Thanks for testing again!

Is there any way to possibly not visibly show the popover/context menu until it is in the new position?

I'll ruminate on this for a bit.

[chandlerprall]

@cchaos I've updated context menu's panel rendering to not transition/animate the initial panel. This positions the panel correctly on initial showing.

[cchaos]

Oh heck yeah! It works and looks soo much better now. The animation on first open was bugging us.