While designing a footprint, you will lose all your work without any warning message, if you press any of the following buttons : "Surface Mount", "Through hole", "Designer", "Demo".  It happened a few time to me, maybe I am getting too old with these tiny icons.

I propose to add a new settings named "Extra confirmation" in the menu Tools->Option->Console. It would be OFF by default, so that experts are not bothered with extra clicks. But when ON, it would trigger a requester window such as "Are you sure?" anytime you click on something that will corrupt values in the calculator or designer. I think these corrupting buttons are limited to this list: "Surface Mount", "Through hole", "Designer", "Demo". 

All for now,

GV