When trying to type a special character into the in-game chat (or anywhere else), nothing happens.

This bug occurs regardless of the Minecraft version (tested in 1.5.1, 1.5.2pre, 13w16a, 13w18b, 13w21b, 13w25a, and 1.6.1) when using the new launcher. It does not occur (again, regardless of Minecraft version, tested in 1.5.1 and 1.5.2pre) when using the “official”/old launcher.

Examples of affected characters are:

• ä (U+E4 LATIN SMALL LETTER A WITH DIAERESIS)
• Ü (U+DC LATIN CAPITAL LETTER U WITH DIAERESIS)
• ß (U+DF LATIN SMALL LETTER SHARP S)
• δ (U+3B4 GREEK SMALL LETTER DELTA)
• … (U+2026 HORIZONTAL ELLIPSIS)

The character ` (U+60 GRAVE ACCENT) is not affected, it can be typed as normal even though it is not included in the main “bold” Minecraft font.