Assembly: System.Web (in System.Web.dll)
The WebPartAdding event is raised by the OnWebPartAdding method just before adding a control to a Web Parts zone. This event provides an opportunity to cancel the process before it is complete. The WebPartAdded event is called after a control has been added to a Web Parts zone.
The method specified in the delegate is called when a WebPartAdding event is raised.
Page developers can provide custom handlers for the event by adding the OnWebPartAdding attribute to the <asp:webpartmanager> element in a page, and assigning a custom method name to the attribute. A custom handler can also be assigned programmatically. For more information on programmatically assigning an event handler, see How to: Connect Event Handler Methods to Events.