> Per-display DPI settings

fwiw, Xorg already had this, since you can set the DPI for each display through RandR/xrandr. In both X11 and Wayland it's up to the toolkit to actually detect the setting and rasterise accordingly.

Wayland actually went backwards in this respect by using "integer scales" (eg, 1, 2, 3) instead of fine-grained DPIs (eg, 96, 192, 288), so using a scale of 1.5 would result in downscale blur (toolkit sees scale as 2, then the compositor scales it down to 75%), whereas in Xorg you could just set the DPI to 144, and the toolkit could theoretically render at the correct resolution. As far as I know Qt was the only toolkit to actually do this automatically, but that's not X11's fault.

Wayland has at least since fixed this in the form of "fractional scaling" [1], but here's [0] an old thread on HN where I complained about it and provided screenshots of the resulting blur.

[0] https://news.ycombinator.com/item?id=32021261

[1] Doing some quick searching it seems like this is still unsupported in Gtk3/Gtk4, maybe planned for Gtk5? Apparently Firefox has only just added support (December 2025), 3 years after the fractional scaling protocol was released. Seems ridiculous to me that Wayland failed to get this right from the start.