View mobile and desktop at the some time

Building responsively is tricky! Would be awesome if the visual editor had a view where you can be viewing desktop and mobile at the same time while building experiences and updating content. This would allow you to see if you're making some adjustments on one device that may be suboptimal for others. Think this would make the most sense in fullscreen mode, and the ability to choose with device is "active" (since we often make device specific changes). The idea is to make changes to one device and see implications on the other device.