Bien...
Coloca este codigo en (general) (Declaraciones) de un formulario
Private Declare Function SetWindowRgn Lib "user32" (ByVal hWnd As Long, ByVal hRgn As Long, ByVal bRedraw As Boolean) As Long
Private Declare Function CreateEllipticRgn Lib "gdi32" (ByVal X1 As Long, ByVal Y1 As Long, ByVal X2 As Long, ByVal Y2 As Long) As Long
Private Sub Form_Load()
Dim Ancho As Long, Alto As Long
Ancho = Me.Width / Screen.TwipsPerPixelX
Alto = Me.Height / Screen.TwipsPerPixelY
SetWindowRgn hWnd, CreateEllipticRgn(2, 2, Ancho, Alto), True
End Sub
