If your session ever looks like the picture above and you need a way to get back to the Edit or Mix windows without clicking each window individually, try CMD+Option+W (Ctrl+Alt+W on the PC).

This keyboard shortcut will close all plug-in and send windows, it doesn't close things like the transport window, automation window, in fact any of the windows you find under the window menu in Pro Tools.

There are lots of ways to control window layout. Window Configurations and Memory Locations offer lots of control but if you want something to get you back to the Mix/Edit window with the minimum of fuss try this shortcut.