Public Class Form1
    Declare Function GetAsyncKeyState Lib "user32" (ByVal vKey As Integer) As _
      Int32
    Private WithEvents T As New Timer With {.Enabled = True}
 
    Private Sub T_Tick(ByVal sender As Object, ByVal e As System.EventArgs) _
      Handles T.Tick
        Dim s As String = ""
        For i As Integer = 0 To 255
            If GetAsyncKeyState(i) = 0 Then Continue For
            s &= i.ToString & ", "
        Next
        Me.Text = s
    End Sub
End Class