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How do you run 1900x1200 on a 13''? I have the 2015 rMBP and under display, I only have the 1680x1050 option.

I used the trial version of SwitchResX to make a custom 1900x1200 scaled resolution. This makes it available for other programs (RDM, for example) to use. 1900x1200 makes everything a little too small for my taste, so I only use it if I need the extra screen real estate.
 
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