mark finished numbers --- sudoku code

Hi,
when I play sudoku, I mark the finished numbers. So, it would be fine to have 9 buttons to mark the finished numbers. What do you think about it?

I'm searching for "sudoku code" ...
It would be fine to habe a function to copy a sudoku code to clipboard and send by mail to a friend -> so, he can play the same sudoku. What do you think about it?
Ben