The wording here is intentionally vague because I don't know very well what the possibilities are and what makes sens for winit. It is safe to say that it would be good for winit to expose some way to indicate whether the application is "dpi-aware" and avoid having the window upscaled by the window manager for apps that don't want this behavior.

On Fedora 25 with wayland (now enabled by default), winit windows are all upscaled on hidpi screens.

cc @vberger