code: func (v *Entry) GetPlaceholderText() (string, error) {
  	c := C.gtk_entry_get_placeholder_text(v.native())
  	if c == nil {
  		return "", nilPtrErr
  	}
  	return goString(c), nil
  }
docs: // GetPlaceholderText() is a wrapper around gtk_entry_get_placeholder_text().