Auto-promotion

I'm not sure how difficult it would be, but it would be a nice feature to have a checkbox on the same page as the game allowing players to quickly turn on/off auto-promotion to Queen.

If you have auto-promotion on but want to underpromote, hold the Ctrl key while moving your pawn and the promotion options will always show up.

Thank you, ProgramFOX, I was unaware of that feature.

And how to do that on a mobile device?