Areas can be made to take up more space in two different ways. One we
call "Maximize Area" that just takes up the rest of non-global space,
so leaving Top Bar and Status Bar and everything in the area unchanged.
The other option is shown as "Fullscreen Area" and it calls the same
operator with a use_hide_panels property. This hides the global areas
and also all regions in the area. This was added as an option for the
stereo 3D pipeline for viewing without the distraction of UI elements
that cause depth issue. #142418 further removed text overlays and the
navigation gizmos. This PR just renames the option to better describe
the result, using "Focus Mode".
Pull Request: https://projects.blender.org/blender/blender/pulls/142605
8ba44fe799