I'm reading the Xcode Quick Tour Guide. Under the heading "Using Interface Builder" of "Editing Project Files" #1 says "In the Groups & Files list, select the project group and double-click MainMenu.nib in the detail view. But there is no group called "project". So I double clicked NIB Files and found MainMenu.nib. Then #2a says In the MainMenu.nib window, click Classes. But there is no "Classes" listed after I double-clikc on MainMenu.nib in the detail view. Has something changed? If so how do I complete this item? Could it be that I'm not in "Interface Builder"? If not, how do I bring up "Interface Builder" (I did everything in the previous lessons).