Thanks for your answers.
Yes, Robert Doc Wright godfearer, it works for me too, but only at the beginning of a working day.
After some hours I don't know why I always have the problem that the window is not immediatly opened but I have to use the space bar to confirm.
I can add also that in the same moment I can't open directly the Window using the combination "window + number", I also cannot stop the voice using the CTRL key.
So navigation between windows becomes a bit uncomfrotable.
Of course ALT Tab works, but it is not the faster way to reach immediatly the window you want, especially when a lot of windows of different programs are opened.
The best way is Windows key plus a number.
Thanks again for any suggestion.