The WebPartsConnecting event is raised by the OnWebPartsConnecting method, and it signals that the connection process has begun (for example, a user has selected a control and clicked a connect verb), but is not yet completed. The event provides an opportunity to cancel a connection before it is complete. If the connection is successfully completed, this event is followed by the WebPartsConnected event.
Page developers can add a custom handler for the event by adding the OnWebPartsConnecting attribute to the <asp:webpartmanager> element, and assigning a custom method name to the attribute.
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)