In GNOME Music (version 3.12.2) there is a little issue in the selection mode. As long as an entry is unchecked, the checkbox hides the frame border of the entry. When activating a checkbox, its background gets (kind of) transparent and reveals the entry's frame border. In addition to this, the buttons in the bottom action bar change their size when selecting/unselecting an entry.
In GNOME Music (version 3.12.2) there is a little issue in the selection mode. As long as an entry is unchecked, the checkbox hides the frame border of the entry. When activating a checkbox, its background gets (kind of) transparent and reveals the entry's frame border. In addition to this, the buttons in the bottom action bar change their size when selecting/unselecting an entry.
Unchecked:
Checked: