How to handle Popup focus navigation

[SatadruBhattacharjee]

The polyfill is excellent, how to handle bringing the focus to a popup and bringing back on last focused element on popup close action. Do we have a depth (z-index) based grouping of focusable elements?
Thanks

[SatadruBhattacharjee]

@jihyerish , is it possible to change the root of the navigation container, so that we can toggle between popup and pages, Thanks