We wrote "Motif in the year 2000" as a state-of-the-toolkit report for SunWorld Online. The assertion there that Sjoerd Mullender's PyMotif is unmaintained was ... exaggerated; in fact, Sjoerd continues to make occasional changes.
Watch this page in July 2000 for more links ...
Kenton Lee's great FAQs are the definitive references for information about Motif and more. Of particular interest: his guide to getting Motif.
ICS generously sponsors the Motif Zone, and Interface Technologies, Inc. sponsors a tutorial on Introduction to Motif Application Development. For many years, SCO has made the invaluable User's, Style, and Programmer's Guides, along with the Programmer's Reference, available on-line.
I frequently compare the Motif and Tk toolkits. As much as I like some of the smart people around Motif, and what they've done with it, I can only echo Spencer Kimball when he says,
I can't adequately convey the pain suffered while programming with Motif. It's a bloated and inflexible toolkit. I'm sure that anyone who's familiar with it would agree that trying to make it conform to your idea of the perfect UI is an exercise in futility. Instead, your UI will simply conform to what you can actually manage to put together that doesn't seg fault when you breathe on it.
Antony Fountain passionately argues that Motif is far from dead.
I co-authored a programmer's introduction to Motif which included an extensive description of third-party tools, and a comparison of Motif and other toolkits.
LessTif is a copylefted Motif work-alike.