1 happens, as long as the bigger part of the window is on the non-Retina display. If the bigger part of the window is on the Retina display, the window only get

1 happens, as long as the bigger part of the window is on the non-Retina display. If the bigger part of the window is on the Retina display, the window only gets a Retina paint event and the non-Retina display shows a downscaled version. Source: manual testing under 10.7.4 with HiDPI resolutions activated using QuartzDebug