Red Menace & HerpsMcDerps nailed it. Those are the things people usually do.
There's also a device called the Tremol No, it came out a couple years ago:
It's a device that can be set to 'fixed bridge mode' by tightening a few clamps so in case some strings break the tuning would still remain intact. I had it on one of my guitars but somehow I learned I didn't really need it - to my ears the sound did change with that thing installed so I removed it. Maybe there's just a tiny change in sound or it was purely a feel thing but I decided to ultimately not use it. It could come handy though if you're gigging - as said, to prevent your guitar going completely out of tune in case of string break (phew - I almost wrote 'spring break', haha). Plus, even the 'open' position with the clamp loosened somehow translated into vibrato system feel and I love to have my vibrato system (almost all of my electrics have a vibrato) to feel smoothly when using it (mostly for more subtle 'scoops' then for dive bombs).
You can buy a guitar with a 'real' fixed bridge so you'd neither need to raise the spring tension nor insert wood blocks or things like the Tremol No.