Option Explicit
 
Private Declare Function GetCursorPos Lib "user32" (lpPoint As POINTAPI) As Long
Private Declare Function GetAsyncKeyState Lib "user32" (ByVal vKey As Long) As _
  Integer
 
Private Const VK_LBUTTON = &H1
Private Const VK_RBUTTON = &H2
 
Private Type POINTAPI
  X As Long
  Y As Long
End Type
 
Private Sub Form_Load()
    Timer1.Interval = 10
End Sub
 
Private Sub Timer1_Timer()
    Static bDown As Boolean
    Dim Result&, P As POINTAPI
    If GetAsyncKeyState(vbLeftButton) < 0 Or GetAsyncKeyState(vbRightButton) < _
      0 Then
        Result = GetCursorPos(P)
        If bDown = False Then
            bDown = True
             If (Me.Left / 15) < P.X And ((Me.Left + Me.Width) / 15) > P.X _
               And (Me.Top / 15) < P.Y And ((Me.Top + Me.Height) / 15) > P.Y Then
                'Maus ist auf Form, also kein Beep
             Else
                Beep
            End If
        End If
    Else
        bDown = False
    End If
End Sub