UI file picker
FileNameSetter[name]
FileNameSetter[Dynamic[name]]
FileNameSetter[name, "Save"]
FileNameSetter[name, "spec", {"type1" -> {"patt11", "patt12", …}, "type2" -> {…}, …}]
- Appearance — default Automatic
- BaseStyle — default { }
- Enabled — default Automatic
- ImageMargins — default 0
- ImageSize — default Automatic
- WindowTitle — default Automatic