Function nf_pick 

#[unsafe(no_mangle)]
pub(crate) unsafe extern "C" fn nf_pick(
    context: *const Context,
    kind: DialogKind,
    answer: &PlaceDesc,
    title: Slot,
    types: Slot,
    folder: Slot,
    name: Slot,
    span: u32,
) -> bool

Asks for a file dialog of kind, shown once the current event finishes, whose answer goes to the state at answer. title, folder and name are borrowed strings, and types a borrowed list of strings; "" and [] leave a setting to the platform.

Safety

See the abi module’s contract; the place’s steps are readable.