Stop iTunes hiding sidebar when browsing store? Using iTunes on the Mac, when I click into the iTunes Store in the sidebar it hides the sidebar.

I think I had to click something to make it do this. But I'm no longer on a small screen, so I'd like to turn this previously helpful feature off. But I can't find what I clicked.

How do I make the sidebar visible when browsing the iTunes Store?
I found it:

View > Use Full Window for iTunes Store