I see what he's getting at. See the attached screenshots.
I think when it's in "thumbnail view," the control bar area at the top should be the same (a solid background color), whether you're hovering on it or not. In other words, when you're displaying the thumbnails, you are interacting with the navigation controls, hover or not.
(ETA: Yes, the text color choice is wrong, but that's a different issue.)
I don't see if you think both are ugly or just when it's transparent. I can make the top bar always opaque when the thumbnails panel is displayed, but I think no need to make it opaque if it's only the music controls or the map is displayed as those are small enough, so some of the users might want to keep them permanently visible while flipping through an album.
and choose thumbnails. Hover around in chrome and see the top of the image appearing and disappearing. In my point of view less atractive. My wish would be to have the (top of the) image not visible at all in thumbnail view.