Occurs when a node is expanded in the System.Web.UI.WebControls.TreeView control.
The TreeView.TreeNodeExpanded event is raised when a node is expanded in the System.Web.UI.WebControls.TreeView control. This allows you to provide an event-handling method that performs a custom routine whenever this event occurs.
If the TreeNode.SelectAction property for a node is set to TreeNodeSelectAction.Expand or TreeNodeSelectAction.SelectExpand, the TreeView.TreeNodeExpanded event is also raised when that node is clicked in the System.Web.UI.WebControls.TreeView control.
For more information about handling events, see Consuming Events.