Assembly: System.Web (in System.Web.dll)
The event is raised by the OnWebPartAdding method after the process of adding a control to a zone has begun. This event provides an opportunity to cancel the process before it is complete. If the adding process is successful, this event is followed by the WebPartAdded event.
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.
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.