code: func (v *Entry) LayoutIndexToTextIndex(layoutIndex int) int {
  	c := C.gtk_entry_layout_index_to_text_index(v.native(),
  		C.gint(layoutIndex))
  	return int(c)
  }
docs: // LayoutIndexToTextIndex() is a wrapper around
  // gtk_entry_layout_index_to_text_index().