Raises the WebPartClosed event to signal that a control has been removed from a page.
Assembly: System.Web (in System.Web.dll)
To close a WebPart control means to remove it from a page so that it is not rendered, and also to place it in a special holding object called a page catalog. A page catalog, which corresponds to the PageCatalogPart control, maintains references to closed WebPart controls for each page. If a PageCatalogPart control is declared on a page within a CatalogZone zone, users can switch the page into catalog display mode, and add back to the page any controls that were previously closed.
The method provides an opportunity for developers to create a custom handler for the WebPartClosed event. Page developers can add a custom handler for the event by adding an OnWebPartClosed attribute to the <asp:webpartmanager> element in a page, and then assigning a custom method name to the attribute. One useful task a developer might carry out in this method is to display a placeholder in place of the closed control, complete with a ToolTip that would inform users how to add the control back to the page.