Sub Bouton()
Dim Lettre As String
Lettre = Right(Application.Caller, 1)
If Right(ActiveSheet.Shapes(Application.Caller).DrawingObject.Caption, 1) = Lettre Then
ActiveSheet.Shapes(Application.Caller).DrawingObject.Caption = ""
Else
ActiveSheet.Shapes(Application.Caller).DrawingObject.Caption = Lettre
End If
End Sub