Is it possible to zoom the current image to fill the window (or the full screen) and then shift back to library or develop mode with all the panels? The L command does not zoom the image up to full window or screen size. Is the a similar command the does make the image as large as possible?
F takes you to full screen, L is just "lights out" so you see what is currently in front of you but without the panels. D and G switch between the Develop and Library module respectively, but as soon as you press those then you exit full screen mode.
Here's some keyboard shortcuts.