ModalPopup extender

ModalPopup extender:

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. When displayed, only the modal content can be interacted with; clicking on the rest of the page does nothing. When the user is done interacting with the modal content, a click of an OK/Cancel control dismisses the modal content and optionally runs custom script. The custom script will typically be used to apply whatever changes were made while the modal mode was active. If a postback is required, simply allow the OK/Cancel control to postback and the page to re-render. You can also absolutely position a modal popup by setting the X and Y properties. By default it is centered on the page, however if just X or Y is specified then it is centered vertically or horizontally.