popup alert in html viewer (MBS)

Hi everybody
i’v used the example MBSWebUIDelegate to get the openfile dialog box in my html viewer… It work great
But i dont know how make it work the ( RunJavaScriptAlertPanelWithMessage ) from the same plug in
Does it work on a external web page that i dont have control on how the dialogbox was construct
Or its just i dont know how initiate that feature