Beware the pre-action “check” button that turns into “call” just as you click it. It’s a terrible moment when you think you are casually ticking the pre-action “check” box just as an opponent to your right goes all-in. If all the players between you and your all-in opponent have already ticked “check/fold”, the box you are in the process of ticking will change at the exact moment you are ticking it, and you will have unintentionally called a huge bet.