Private Sub addtxt_Click(sender As Object, e As EventArgs) Handles addtxt.Click
Dim n As String
n = InputBox("thêm")
If TreeView1.SelectedNode Is Nothing Then
TreeView1.Nodes.Add(n)
Else
TreeView1.SelectedNode.Nodes.Add(n)
TreeView1.SelectedNode = Nothing
End If
End Sub
