Check element is link before return

[mattheu]

On IE11, you cannot select an item by clicking on the actual thumbnail image in the explorer. It works fine if you click the title, or the area around the image.

I think this problem is caused by a quirk in IE, where event.target.href returns the image src. As you are checking this isn't empty befor toggling the selection, this breaks on IE.

A simple fix is to check that the event target with an href is also a link element.