True fullscreen for 21:10 Netflix videos on ultra-widescreen LG 34UM95.
Zero permissions extension to allow viewing letterbox movies on Netflix in full 21:9 3440x1440.
Alt+W - enable/disable ultra-widescreen scaling, or click the icon in the location bar when viewing a movie.
You have to manually switch to fullscreen.
Source is available here - https://github.com/johnmccabe/netflix-ultrawidescreen
Disclaimer: Netflix, and LG are registered trademarks and have no affiliation to this extension.