> What will you do when you want to use a 4K monitor? This is not to be dismissive. I am genuinely curious if HiDPI works on motif.

Yes, xrandr -scale. Works fine for everything. Even better than Windows (which, for some reason, only scales some programs, not all)

You would set an appropriate size in .Xresources or somesuch.

I can't speak for Motif but Fluxbox works fine on my 4K monitor