<System.Runtime.InteropServices.DllImport("user32")> _
Public Shared Function GetWindowThreadProcessId _
    (ByVal hWnd As Integer, ByRef lpdwProcessId As Integer) As Integer
End Function
 
'Aufruf      
Dim hwnd As Integer = Me.Handle.ToInt32()
Dim pid As Integer
 
GetWindowThreadProcessId(hwnd, pid)