Adventure mode does not prevent dyeing signs

How to reproduce

1. Place a sign with text on it
2. Get some dye
3. Enter adventure mode
4. Use dye on sign

Note

Since adventure mode players can't edit blocks they should not be able to dye the sign.
This is important because important information is often communicated on signs in maps and areas where the player is expected not to be able to break stuff. Changing the color may cause ugliness or in the worst case, cause the sign to become very hard to read.