Weird problem, I cannot shift+2 an item in my inventory, but every other combination works (e.g. shift+1, shift+3, shift+4) but not shift+2. This is on Linux Mint 17 x64, using the latest java. Happens in singleplayer and SMP. Doesn't happen in Windows.
Shift+2 doesn't do anything (Linux Mint 17 Cinammon x64)