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Do any desktop system handle mixed DPI well? I mainly use Linux so I don't know, but one of my work laptops have windows on it and it freaks out every time I connect it to a 4k monitor. At least in linux I can use triggers and xrandr [1] to manage it even if it's not pretty, never figured out how to do it automatically in windows. Edit: I am using KDE/Qt apps for 99% of my gui stuff. Gnome etc might be worse. [1] htt…
Windows handles it perfectly (anecdotal). Not sure what do you mean by freaking out.
At least that's how it was for me when I used a high dpi display (160 dpi) 2 yrs ago. (I switched back to 90dpi at some point, so they might have improved it by now)