TreeView.BeforeCheck Event

 
System_CAPS_noteNote

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Occurs before the tree node check box is checked.

Namespace:   System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

member BeforeCheck : IEvent<TreeViewCancelEventHandler,
    TreeViewCancelEventArgs>

System_CAPS_noteNote

Setting the TreeNode.Checked property from within the BeforeCheck or AfterCheck event causes the event to be raised multiple times and can result in unexpected behavior. For example, you might set the Checked property in the event handler when you are recursively updating the child nodes, so that the user does not have to expand and check each one individually. To prevent the event from being raised multiple times, add logic to your event handler that only executes your recursive code if the Action property of the TreeViewEventArgs is not set to TreeViewAction.Unknown.

For more information about how to handle events, see Handling and Raising Events.

The following code example updates all the child tree nodes of a TreeNode when the user changes its checked state. This code requires that you have a Form with a TreeView that has TreeNode objects in its TreeNodeCollection. The TreeNodeCollection should have tree nodes with child nodes.

No code example is currently available or this language may not be supported.

.NET Framework
Available since 1.1
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