Ask "are you sure?" before exiting the deck options screen

Often when I make changes to the deck options, I want to make them to each deck options group, of which I have a lot (>30; almost one for each deck). Not only once has it happened that I forgot to press “save” and instead I just esc-left the deck options screen. So, I have to make all the clicks again.

Perhaps this happens to more people, and new users might not even be aware of it. Might as well be a niche problem, though.