code: func (v *AppChooserButton) SetActiveCustomItem(name string) {
  	cstr := C.CString(name)
  	defer C.free(unsafe.Pointer(cstr))
  	C.gtk_app_chooser_button_set_active_custom_item(v.native(), (*C.gchar)(cstr))
  }
docs: // SetActiveCustomItem() is a wrapper around gtk_app_chooser_button_set_active_custom_item().