I'm having trouble understanding the coordinates of the NSViews inside an NSTabView. To create the extremely simple XIB that I have attached, - Run Interface Builder and create a new XIB (Cocoa Application Template) - Set the window's width to 346 and height to 362 in its size inspector - Place an NSTabView on the window. Resize and position the NSTabView so that it snaps to the blue guides along all the edges of the window. Here are all the coordinates from all the size inspectors Content View (0, 0) Top Tab View (20, 20) NSView (10, 333) NSView (10, 333) I'd appreciate it a lot if I could get some help understanding where the (10, 333) comes from. Thanks!