Private Function SubtractRectangle(ByVal rect1 As Rectangle, ByVal rect2 As _
  Rectangle) As Rectangle
        Return New Rectangle(rect1.X - rect2.X, rect1.Y - rect2.Y, rect1.Width _
        - rect2.Width, rect1.Height - rect2.Height)
    End Function

Dim temprect As Rectangle = SubtractRectangle(ownerrect, area2show)
            Select Case temprect
                Case temprect.X < 0
                    'das hier geht schon nicht !!!!
                Case Else
                    'normalfall pfeil links oben
 
            End Select