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TreeView.BeforeLabelEdit Event

Occurs before the tree node label text is edited.

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

'Declaration
Public Event BeforeLabelEdit As NodeLabelEditEventHandler

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

The following code example demonstrates how to use the BeforeLabelEdit AfterSelect and TopNode members. To run this example, paste the following code in a form that contains a TreeView control that is named TreeView1. Call the InitializeTreeView method in the form's constructor or Load method.

Private Sub InitializeTreeView()

    ' Construct the TreeView object. 
    Me.TreeView1 = New System.Windows.Forms.TreeView

    ' Set dock, location, size name, and tab order 
    ' values for the TreeView object. 

    With TreeView1
        .Dock = System.Windows.Forms.DockStyle.Left
        .Location = New System.Drawing.Point(0, 0)
        .Name = "TreeView1"
        .Size = New System.Drawing.Size(152, 266)
        .TabIndex = 1
    End With 

    ' Set the LabelEdit property to true to allow the  
    ' user to edit the TreeNode text. 
    Me.TreeView1.LabelEdit = True 

    ' Declare and create objects needed to populate  
    ' the TreeView. 
    Dim file, files(), filePath As String
    files = New String() {"bigPresentation.ppt", "myFinances.xls", _
        "myResume.doc"}
    filePath = "c:\myFiles" 
    Dim nodes As New System.Collections.ArrayList

    ' Create a node for each file, setting the Text property to the  
    ' file's name and the Tag property to file's fully-qualified name. 
    For Each file In files
        Dim node As New TreeNode(file)
        node.Tag = filePath & "\" & file
        nodes.Add(node)
    Next 

    ' Create a new node named topNode and add the ArrayList of  
    ' nodes to topNode. 
    Dim topNode As New TreeNode("myFiles", _
        nodes.ToArray(GetType(TreeNode)))

    topNode.Tag = filePath

    ' Add topNode to the TreeView.
    TreeView1.Nodes.Add(topNode)

    ' Add the TreeView to the form. 
    Me.Controls.Add(TreeView1)
End Sub 

Private Sub TreeView1_BeforeLabelEdit(ByVal sender As Object, _
    ByVal e As NodeLabelEditEventArgs) Handles TreeView1.BeforeLabelEdit

    ' Determine whether the user has selected the top node. If so, 
    ' change the CancelEdit property to true to cancel the edit.   
    If (e.Node Is TreeView1.TopNode) Then

        e.CancelEdit = True
        MessageBox.Show("You are not allowed to edit the top node")
    End If 


End Sub


...


' Handle the After_Select event. 
Private Sub TreeView1_AfterSelect(ByVal sender As System.Object, _
    ByVal e As System.Windows.Forms.TreeViewEventArgs) _
        Handles TreeView1.AfterSelect

    ' Vary the response depending on which TreeViewAction 
    ' triggered the event.  
    Select Case (e.Action)
        Case TreeViewAction.ByKeyboard
            MessageBox.Show("You like the keyboard!")
        Case TreeViewAction.ByMouse
            MessageBox.Show("You like the mouse!")
    End Select 
End Sub
		The following method shows the use of the LabelEdit property.
		Add this method to a form containing a ListBox control named ListBox1.

		Call the method in the constructor or Load method of the form.


...


		The following class inherits from the Button class and overrides
		the OnMouseHover and OnMouseMove methods to give the button
		some special behavior. To use this example create a new form and copy paste this class in the same file, after the form class.  Add a button of
		type FunButton, defined in the code example, to the form. 

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
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