code: func PrintRunPageSetupDialogAsync(parent *Window, setup *PageSetup,
  	settings *PrintSettings, cb PageSetupDoneCallback, data uintptr) {
  
  	pageSetupDoneCallbackRegistry.Lock()
  	id := pageSetupDoneCallbackRegistry.next
  	pageSetupDoneCallbackRegistry.next++
  	pageSetupDoneCallbackRegistry.m[id] =
  		pageSetupDoneCallbackData{fn: cb, data: data}
  	pageSetupDoneCallbackRegistry.Unlock()
  
  	C._gtk_print_run_page_setup_dialog_async(parent.native(), setup.native(),
  		settings.native(), C.gpointer(uintptr(id)))
  }
docs: // PrintRunPageSetupDialogAsync() is a wrapper around gtk_print_run_page_setup_dialog_async().