code: func (v *ComboBoxText) Append(id, text string) {
  	cid := C.CString(id)
  	ctext := C.CString(text)
  	defer C.free(unsafe.Pointer(cid))
  	defer C.free(unsafe.Pointer(ctext))
  	C.gtk_combo_box_text_append(v.native(), (*C.gchar)(cid), (*C.gchar)(ctext))
  }
docs: // Append is a wrapper around gtk_combo_box_text_append().