Public Class Form1
 
    Private Declare Function FindWindow Lib "user32" _
      Alias "FindWindowA" ( _
      ByVal lpClassName As String, _
      ByVal lpWindowName As String) As Long
 
 
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        Dim a As Long
        a = FindWindow( , )
        MsgBox(a)
 
    End Sub
End Class