Public Class Form1
   Private Declare Ansi Function SendMessage Lib "user32.dll" Alias _
     "SendMessageA" (ByVal hwnd As Integer, ByVal wMsg As Integer, ByVal wParam _
     As Integer, ByVal lParam As String) As Integer 
    Private Declare Function GetForegroundWindow Lib "user32" Alias _
    "GetForegroundWindow" () As Long
 
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        Dim intParameter As Integer
        Const WM_SCROLL = 277
        intParameter = 1
        SendMessage(GetForegroundWindow, WM_SCROLL, intParameter, 0)
    End Sub
End Class