Ref player: cannot select source menu items appearing lower than seekbar

Created by: davemevans

In the reference player, select and play any live source, or an ondemand source skipped til near the end. Now attempt to play an item in, for example, "Axinom Test Content (modern)" submenu, that appears lower on the screen than the seekbar. Notice that the seekbar appears on top of the menu and it is not possible to select any items below the seekbar.

div#seekbar-play probably has higher z-index than source menu so it appears on top of the menu and presumably causes mouseleave to be fired at menu on mouseover.