Screen Shot 2013-04-11 at 4.45.12 PM.jpgYes OS X, and mine simply doesn't have it, regardless of how much I mouse over anything..! The only time there's a fullscreen toggle button is on launch where you can select recent projects. But toggling that just turns that window into fullscreen.
Haven't happened to me with SA but with other Mac Apps that get their prefs corrupted and tries placing the window in (x,y)-positions that are off-screen. When this happens on Windows you can always do Alt-Space, Down Arrow, Enter, Right Arrow and then move the mouse around.
Up up down down left right left right doesn't work. Can't move the window around in Expose. I think this is a Sencha Architect bug (although by the looks of it, it's quite rare), and one thing that's missing is a menu item to get the app out of full screen mode (eg under Window - Exit Full Screen).
Mucking around with this further - I quit Architect, relaunched it. In the opening dialogue (recent projects) there is a fullscreen toggle button. I tapped that, and then loaded my project. Lo and behold, the fullscreen button now appears in the menu and I can unfullscreen the app. I've tried to recreate the bug of the disappearing full screen button but haven't yet.