After playing some of the Switch Picross games I noticed a nice convenience feature that when you complete a row/column it automatically fills the remaining open spaces with an X.

This feels like it would be a nice option to flip on, as it removes a good amount of rote actions, though I could see a misclick on a 1 column causing issues.

One way to implement this that would still leave it as an action the user has to take is allow them to right click on the greyed out numbers to fill all remaining spaces with an X.