[computer]

Ah yes, I see. I just tried it out, here's GIMP with a 256 DPI:

http://i.imgur.com/2GpqyND.png

The title-bar size is configured in pixels, so that could be fixed easily by the user, but icons, both in the GIMP and in the native window don't resize well. It seems the DPI scaling is only applied to text, and only text-containing elements are scaled accordingly.

[Touche]

Arch Wiki is a good resource for this: https://wiki.archlinux.org/index.php/HiDPI

And apparently there is an update today! Can't wait to try this out.

[computer]

Note that the setting mentioned there (Xft -> DPI) is the same as the one in my screenshot, found at Appearance -> Fonts.