Yeah the iOS multitasking view tracks all the way back to windows in OS X 10.5 Exposé being actual windows instead of snapshots, and the parlor trick of QuickTime player windows continuing to play video when minimized to the dock all the way back in 10.0 (and perhaps the 10.0 public beta, I forget). It’s the kind of thing that family of operating systems has handled well for a long time.