I was borrowing a flame 2 sword from Unkownrider (before I had my own) and in a heated battle hit the q key. Luckily Unkown had seen where it landed and grabbed it. He told me to switch my throw key and let me use again Sorry again oh great leader!
To completely turn it off, just go to your options.txt in you .minecraft folder, go in and make the key_key.drop: line 00 (ZERO ZERO) then save and exit, next make the file read only, so minecraft won't write back the default.
Oh yea also, just wanted to point out, you can still throw crap away after this, just drag from your inventory of course.
I had a ton of enchants in my "Holy crap these are expensive" chest. When the map change rolled around I was too lazy and forgot to do the copy/paste application. Bye bye items.
