Autosuggest in modal overflow problem

[brian-smith-tcril]

Minimal repro (playground)

Observed

Expected

Dropdown goes outside of modal as shown in this issue openedx/modular-learning#117

[rpenido]

Just to give some context, it is not associated with z-indez. The problem is that the Dialog and Dialog Body have d-flex and are expanding (and adding a scroll), preventing the popup from overflowing correctly.

Putting position: fixed !important; in the .pgn__form-autosuggest__dropdown class fixes the overflow but creates many positioning problems.