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Twitter post by Daniel Feldman (@d_feldman): Linux is the only major operating system to support diagonal mode (credit [Twitter] @xssfox). Image shows an untrawide monitor rotated about 45 degrees, with a horizontal IDE window taking up a bottom triangle. A web browser and settings menu above it are organized creating a window shape almost like a stepped pyramid.
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Google has you covered: enter askew into the search bar and hit enter
And then there’s this unofficial version… - you should try it on mobile, as it uses the sensors to adjust to the angle your holding your phone.