Dim Detener As Boolean
Private Sub btnDetener_Click()
Detener = False
End Sub
Private Sub btnGirar_Click()
Detener = True
While Detener
Hoja1.Shapes("flecha").IncrementRotation Range("D10").Value
velocidad = Timer + Range("D14").Value / 1000
While Timer < velocidad
VBA.DoEvents
Wend
Wend
End Sub