gtk/gtk.go
func (v *FileChooser) AddFilter(filter *FileFilter) {
	C.gtk_file_chooser_add_filter(v.native(), filter.native())
}
func (v *FileChooser) AddFilter(filter *FileFilter) {
	C.gtk_file_chooser_add_filter(v.native(), filter.native())
}
// AddFilter is a wrapper around gtk_file_chooser_add_filter().