Hi Filippo,
Nice job !
I agree with the others that an adaptation to other countries is a MUST. Here you find a lot of layouts for different countries
Keyboard layout - Wikipedia, the free encyclopedia
I would have seen the '123' button for the numeric keyboard directly integrated into the keyboard and not as an extra outsides button.
It would also be interesting to have the Height (and Width, not so important) parameters (read only) available to know where to place other controls.
Best regards.