code: func (ps *PrintSettings) GetPaperSize() (*PaperSize, error) {
  	c := C.gtk_print_settings_get_paper_size(ps.native())
  	if c == nil {
  		return nil, nilPtrErr
  	}
  	p := &PaperSize{c}
  	runtime.SetFinalizer(p, (*PaperSize).free)
  	return p, nil
  }
docs: // GetPaperSize() is a wrapper around gtk_print_settings_get_paper_size().