Private Declare Function BlockInput Lib "user32" (ByVal fBlock _
            As Integer) As Integer
 
    Const API_FALSE As Long = 0&
    Const API_TRUE As Long = 1&
 
    Private Sub formMain_Load(ByVal sender As System.Object, _
              ByVal e As System.EventArgs) Handles MyBase.Load
        Dim t As New Timers.Timer(1000)
        AddHandler t.Elapsed, AddressOf TimerElapsed
        t.AutoReset = True
        t.Start()
        Dim ret As Integer = BlockInput(API_TRUE)
        Debug.WriteLine(ret)
    End Sub
 
    Private Sub TimerElapsed(ByVal sender As Object, ByVal e As _
      Timers.ElapsedEventArgs)
        Static i As Integer
        If i > 10 Then
            Dim ret As Integer = BlockInput(API_FALSE)
            Debug.WriteLine(ret)
        End If
        i += 1
    End Sub