Since you added the double-click to view artwork feature to this, it's messed up double-clicking to play an album in certain circumstances. It occurs when you are playing an album in the far-right column of the artwork view and you double-click the album directly underneath the one that's playing.
For example, let's say I'm playing this album: -
When I double-click the Zapp album that's underneath it, rather than playing the album, it opens the artwork: -
This occurs because when the expanded view opens, the mouse pointer is where the artwork is, so the double-click action is being registered as "open artwork" instead of "play album". If the album is in a different column, then when the expanded view opens, the mouse pointer isn't over the artwork so the double-click action correctly registers as "play album".