Assembly: System.Web (in System.Web.dll)
Page developers can provide custom handlers for Web Parts events by adding an OnSelectedWebPartChanging attribute, OnWebPartClosing attribute, or OnWebPartDeleting 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.
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.