Can not overflow size of a parent div (like in-line in a data grid) unless overflow: visible (but then parent can not scroll)

[NOA-Alex]

I want to use the Custom Dropdown Widget within a Data Grid 2 table. For example to set the language of a document or the country of a phone number while in table view.
The table is using virtual scrolling on x and regular scrolling on y (if the table is wider than the parent). The regular dropdown opens and shows beyond and on top the x or y scrollbar. While the Custom Dropdown Widget activates and stays within the view surrounded by the scrollbars.
The only way I can make the Custom Dropdown Widget extend beyond area is to set overflow: visible. But then the table does not has any scrollbars at all (even when they are needed when the table is too wide or too long).
Trying to work with position relative, absolute, z-index, etc. did not solved the issue.

[fpellanda]

This PR looks promising for the issue. #47