I am still puzzled about paragraph-at-a-time typesetting in groff. How does Utroff deal with even simple changes of line length, e.g. for flowing text around an image as in the following trivial example. A robust version that allows for intervening page or paragraph breaks would pose even more difficulty.
.wh \n[nl]+3 `in +1.5i .wh \n[nl]+3+2i `in -1.5i Paragraph text here ... The conundrum is that the placement of the picture is defined by line breaks, but with paragraphwise justification, the line breaks depend on where the picture is. Unjustified text is becoming quite common these days, presumably because the added shape of text helps the eye maintain vertical sync. I personally prefer it. On unjustified text, fmt (which uses an algorithm purported to be like Knuth-Plass) does a worse job than nroff. Its scoring method has a significant chance of making a paragraph less uniform than nroff--perhaps because it isn't sufficiently "like Knuth-Plass". But it also has a habit that seems intrinsic to paragraphwise justification: each paragraph appears to have its own distinct line length. How does Utroff address this pitfall? Doug