Instead of forwarding the flush to the view, using CoreGraphics to blit the backing store to the window, we do everything in flush(), and use higher level AppKit APIs to do the blit. This simplifies the flow and code quite a bit, and also supports blitting of individual regions in a flush instead of the whole bounding rect. Change-Id: I2173c1a7763fe652a94125c7e3ae93a655412cd3 Reviewed-by: Jake Petroules <jake.petroules@qt.io> Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>