Imports System.Collections.Generic
Imports System
Public Class Form1
    Dim num As Integer = 0
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        ListBox1.Items.Add("One")
        ListBox1.Items.Add("Two")
        ListBox1.Items.Add("Three")
        VScrollBar1.Minimum = 0
        VScrollBar1.Maximum = ListBox1.Items.Count
        VScrollBar1.SmallChange = 1
    End Sub
    Private Sub cmdPorts_Click(sender As Object, e As EventArgs) Handles _
      cmdPorts.Click
        Application.Exit()
    End Sub
    Private Sub sel()
        For i As Integer = 0 To ListBox1.Items.Count - 1
            If i = num Then
                ListBox1.SetSelected(i, True)
            End If
        Next i
        TextBox1.Text = (ListBox1.SelectedItem.ToString)
    End Sub
 
    Private Sub VScrollBar1_Scroll(sender As Object, e As ScrollEventArgs) _
      Handles VScrollBar1.Scroll
        If e.Type = ScrollEventType.SmallIncrement Then
            Debug.Print("User clicked the right (or bottom) scroll arrow")
            If num < ListBox1.Items.Count - 1 Then
                num = num + 1
            End If
        End If
 
        If e.Type = ScrollEventType.SmallDecrement Then
            Debug.Print("User clicked the left (or top) scroll arrow")
            If num > 0 And num <= ListBox1.Items.Count - 1 Then
                num = num - 1
            End If
        End If
        sel()
    End Sub
End Class