I have one other bit of feedback to give on this.....
I have the option set so that if I double-click on an album, it starts playing the album.
Let's say that I've clicked on an album and the new expandable view is opened. I can no longer double-click on any album that's below that, because this happens: -
So in the GIF, I have the expandable view open for the Joyce Sims album in the top row. I then try and double-click on the Lillo Thomas album underneath that to play it, except the first click causes the expandable view to open, which then shifts the album art up, so the second click actually clicks on the "Hot Love" track that happens to be where the mouse pointer is.
I'm not sure if there's a good way to address this, but if you can come up with something, that would be great!