Seeing guis in Studio?

The last time I used Studio I was working with guis and uncheckmarked some button that said something like "see active guis in studio". Anyway, when I unchecked it it made all the guis I was working on disappear from the active screen so they weren't cluttering up it (they're still in the game, mind you, it just made it so I couldn't see them floating there while I worked on the game). But now I've come back and I forgot what button I hit to make it do that? Does anyone know what box I'm talking about and where to locate it?