Hi Rubén
Thanks for your explanations (also for practical advice like the one for not using %) and of course your sample. We now have a choice between two solutions.
When I tried to set it up, I had been confused by the view box. You and jbacelar make it look simple!
I have no doubt that one of the two will soon be implemented. It will be developer's choice.
y muchas gracias para nuestros dos amigos (a bit longer than Notjohn)