Special (unicode) characters aren't working

Starting from 1.8.2-pre6 many unicode characters aren't displayed properly.

Steps to reproduce:
1) Launch 1.8.2-pre6
2) Type in any text field (the chat, for example) special characters, for example "à", "è", "ò", "ù"

This also "works" for entity custom names, item names and whatever could use special characters (menus, splashes, etc...).