I know who Jean Sibelius was, but Ucklak was talking about some "Sibelus" software. "Sibelius" is a well-known music notation package. There might be a plugin you need to install to view score sheets created with it.
Well, I was just pissed off a little bit by someone complaining about a piece of software they don't even know how to spell. I must admit that my post wasn't worth more than the original troll. Sorry.