Cannot type non-ascii unicode characters on signs in Mac OS

I am unable to type non-ascii unicode characters, such as cyrillic letters or "™" "«", on signs, either by using cyrilic keyboard layout, or by pressing 'alt' to enter special characters.

Typing of non-ascii characters works correctly, both in cyrilic keyboard layout, and with alt key in any keyboard layout, in:

• Chat
• Written books
• Anvil item rename

The same occurs in 1.4.2 and 1.4.3 prerelease.