Hi,
Because the Flash/Silverlight limited ,
So Uploader only support this logic :
1 - user click the button (actually click on the Flash/Siverlight transparent layer, not on the button)
2 - uploader fire the CuteWebUI_AjaxUploader_OnBrowse event.
you can put your login in that function , decide show the dialog or cancel it.
There's no other way to do more. Setteing the onclick event on the button also have no effect.
Regards,
Terry