So, this isn't THAT important of a bug. It's just that when we hold shift and press a number, a saved slot opens. The problem is that first of all, there's no way to change this, and second of all, for those of us who have a broken scroll wheel and have to use the numbers to change slots because we can't afford a new mouse... well... this is pretty dang irritating. So, like, when I am building something and I have to hold shift for the purpose of placing something, and I want to switch to a different block, my entire inventory is cleared to an unsaved slot. I then have to reload EVERY block, just to have myself do the same thing 5 minutes later.
It's a cool feature, it really is.... for those who have working scroll wheels. For those of us who don't... it's pretty aggravating. Maybe add a controls option or, if you can't, maybe switch which combinations of keys load the saved inventories?