> Linux support is spottier, especially when using multiple displays of varying DPIs, but even Gnome works pretty well on a HiDPI laptop these days.

Actually, Gnome is the only one that doesn’t do proper HiDPI support. It only supports 96 and 192dpi - not any other ratio.

In comparison, Qt supports different ratios for every screen, all ratios specified as float – you can even scale up, down, whatever.

The environment variable used is

    QT_SCREEN_SCALE_FACTORS=DisplayPort-2=1.75;HDMI-A-0=1.08;

I'm using Ubuntu 16.04 on a Dell XPS 13 (3200x1800) and it works well as long as I use 2.0 as the magnification value. Other values such as 1.83 are broken.

I'm using XFCE (Debian unstable) on a Zenbook (3200x1800) and that works really well too. There isn't a magnification value to set - rather you set the display DPI.