Public Class frmTreeviewDemo
 
 
    Dim WithEvents trv As New TreeView With
        {.Parent = Me, .Size = New Drawing.Size(200, 500)}
 
 
    Private Sub frmTreeviewDemo_Load(sender As Object,
                                     e As EventArgs) Handles MyBase.Load
        Me.Size = New Size(220, 550)
 
        'Testdaten erstellen
        Dim tn1, tn2, tn3 As TreeNode
        For i As Integer = 65 To 70
            tn1 = trv.Nodes.Add(Chr(i), Chr(i))
            For k As Integer = 65 To 70
                tn2 = tn1.Nodes.Add(Chr(i) & Chr(k), Chr(k))
                For l As Integer = 65 To 70
                    tn3 = tn2.Nodes.Add(Chr(i) & Chr(k) & Chr(l), Chr(l))
                    For m = 65 To 70
                        tn3.Nodes.Add(Chr(m))
                    Next
                Next
            Next
        Next
 
    End Sub
 
 
    Private Sub trv_BeforeExpand(sender As Object,
         e As TreeViewCancelEventArgs) Handles trv.BeforeExpand
 
        If e.Node.Parent Is Nothing Then
            trv.CollapseAll()
        Else
            For Each tn As TreeNode In e.Node.Parent.Nodes
                tn.Collapse()
            Next
        End If
    End Sub
 
End Class