Описание тега modalpopupextender
The ModalPopupExtender is part of the AJAX Control Toolkit for ASP.NET
The ModalPopupExtender is part of the AJAX Control Toolkit for ASP.NET
The ModalPopup extender allows a page to display content to the user in a "modal" manner which prevents the user from interacting with the rest of the page. The modal content can be any hierarchy of controls and is displayed above a background that can have a custom style applied to it.