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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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Did you check the actual TV settings? Some of them let you adjust where picture is displayed iirc.
It only had two modes for the VGA source, 16:9 and 4:3. The 16:9 is the right ratio for the laptop but had the offset issue. The 4:3 makes it stretched out / squashed, but it doesn't have the offset issue.