Generally you apply a curved white with like 60% transparant gloss over it, making it "shine" a bit more. Let me try to find a example I made for Disco users.
[Edit]
If you look closely to the logo of the OSI on the left there's a vague curved line going upwards from halfway the logo. It makes a userbar "come alive" a bit more.
But overall I like your work.
[Edit 2]
Can't remember if I made or "fixed" this one, but this is a perfect clear example on the "gloss".