I think, monitors dpi settings on Haiku is to small, it (GUI elements) must be bigger. I tried out Haiku-OS on 96, 102, 120 dpi monitors and all GUI elements and fonts is too small. Good realisation of dpi setting have Mate desktop (gnome2) on linux.
This is visual explanation, font in the exampleprint.pdf is 10 pt, and printed page is the same with 10 pt:
this is in haiku-os:
this is in mate desktop on linux:
