I watched this movie over 10 years ago, so it probably was filmed in the 90s. It was very odd and slow-paced, set somewhere in Europe, I think. My recollection of the plot goes like this:
It's about an old man famous for his operas but he has already gone into retirement, something about losing his inspiration. However, for some reasons he is struggling to write one more music piece. Into the story comes a young man who arrives of a sudden and starts living in the same house, becoming something akin to an assistant, although there is no clear explanation of what he does. In a couple of scenes he is seen sitting on the windowsill of high round-shaped window in the composer's house, and the young man bleeds from unexplained injuries. It lends the movie an aura of mystery, I guess? Almost by the end, when the old man has managed to write his final opera, the composer has a close-call with a heart attack but he survives, while the young man is somewhere in a bathroom washing off blood from his arms. In the end the young man simply goes away.
That's what I remember, I wonder if someone knows about this movie?

Amadeus

@Maob812:

No, thank you, but no. The movie I am trying to find is set around the 90s probably (cars, trains, land phones, the like). More than about the music composition per se, it's about the composer's life, his relationship with this mysterious assistant, his wife and his peers, oh and his heart condition. There's even a young woman who shows up at mid movie because the old man and the young one are looking for a proper secretary to take musical notes etc.