Setting the TreeNode.Checked property from within a TreeView.BeforeCheck or TreeView.AfterCheck event handler causes the event to be raised multiple times and can result in unexpected behavior. To prevent the event from being raised multiple times, add logic to your event handler that only executes your recursive code if the TreeViewEventArgs.Action property of the System.Windows.Forms.TreeViewEventArgs is not set to TreeViewAction.Unknown.

For more information about handling events, see Consuming Events.

Namespace: System.Windows.Forms
Assembly: System.Windows.Forms (in System.Windows.Forms.dll)
Assembly Versions: 1.0.5000.0, 2.0.0.0