What Is This Square For?

[pedz]

I have iTunes 11.4 on a Mac running 10.6.8. The iTunes has this odd button (see attached). When I click it, an empty rectangle opens up. Is something wrong? I scanned around Google images and I can't find anyone else with this button. Do other folks have this button? And if so, what is in the rectangle when its opened?

 

[jbarley]

Wish List preview box.

 

[pedz]

Thank you!

Initially, my rectangle was completely blank. I added something to my wish list and now it renders much like yours.

 

[jbarley]

Thank you!

Initially, my rectangle was completely blank. I added something to my wish list and now it renders much like yours.

I have nothing in mine and it renders just as I posted.
Glad to be of some help with your question.