The button a player picks in the overlay is stored like the one a dialog without
UI picks, and sceMsgDialogGetResult, which returns it, is exported by
libSceMsgDialog.native only.
The silent stub entry said message dialogs show no UI. Only user message
dialogs with button type 0, 1, 3 or 4 are shown now; the entry lists the kinds
and the situations that still finish on the second status call.