popup() is generally better but it has a certain advantage that it does
not require a run loop to work, therefore platforms (like WASM) can use
it without resorting to extra measures (like asyncify).
Task-id: QTBUG-106389
Backport-to: 6.4 6.4.0
Change-Id: I87bde677f84048af82cc9aadd982284bdba41e69
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>