using System; using System.Drawing; using System.Collections; using System.ComponentModel; using System.Windows.Forms; using System.Data; namespace ComboBox { public class Form1 : System.Windows.Forms.Form { private TreeView mTree = new TreeView(); public Form1() { ClientSize = new System.Drawing.Size(136, 136); Controls.Add(mTree); mTree.Nodes.Add(new TreeNode("B")); mTree.Nodes.Add(new TreeNode("C")); mTree.Nodes.Insert(0, new TreeNode("A")); } static void Main() { Application.Run(new Form1()); } } }