Music/Art Artist/Musician

Musicians who are fine artists, and fine artists who are musicians that I know of the top of my head, include:
Brian Eno, whose work was/is (?) on show at the I.C.A, The Secret Public exhibition,
Devandra Banhart, whose work I've seen exhibited in 'Uncertain states of America',
Patrick Wolf, uses his own art work in his music releases,
as does Bat for Lashes, singer Natasha Kahn who studied film and music at art school, and early influences on her work led her to sound installations, performance and animations.
Bat for Lashes have played alongside Devandra Banhart and CocoRosie. CocoRosie has been joined by Antony, of Antony and the Johnsons and Patrick Wolf, who sang Antony's part at a London show.

It seems the links are endless, musicians/artists seem to form a group, through shows and colloborations, the links grow and grow.
The musicians I talk of are artists in my eyes. I don't know if there is a criteria which makes music art, I think art is a blur, peoples perceptions of it are different and there is no real definition of 'art'.
Music paints a picture in our minds, it uses words and melodies to form a picture for us, is it another language of art? Another one of expressing ourselves in an 'artistic nature'.