Private Sub Page_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
        If Not IsPostBack Then
            ListBox1.Items.Add("abc1")
            ListBox1.Items.Add("abc2")
            ListBox1.Items.Add("abc3")
            ListBox1.AutoPostBack = False
        End If
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        ListBox1.Items.Add(TextBox1.Text)
    End Sub
 
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button2.Click
        Label1.Text = "Selected item: " + ListBox1.SelectedValue.ToString()
        ListBox1.Items.Remove(ListBox1.SelectedItem)
    End Sub