And it was based or at least inspired on the previous XForms[1] toolkit – the one with way too many bevel shapes for buttons etc., not the XML thing. Probably at least partially done because XForms wasn't open source, and to provide a more "modern" C++ API.
Meanwhile, XForms has been open-sourced, but FLTK being in a different language and having evolved a bit since its creation didn't suffer from the problems Lesstif had and is standing on its own rather well. And despite being C++, it pops up rather often when you're looking for GUIs with decent language bindings (e.g. for Lua or Rust). Probably because it's less a moving target than Qt or, heck, Gtk.
Rakarrack <https://rakarrack.sourceforge.net/> has a GUI written in FLTK. It was my earliest adventure with guitar effects and DSP (ca 2008); it ran on a potato laptop and still kept up, which made the whole setup actually viable for spontaneous jam sessions at other people's places.
This is really nice, thanks for sharing. Looking back, the obvious inspiration here, Classic Windows, was a remarkably good user interface. (Or, many people simply have a soft spot for it, because we used it for a very long time.)
I imagine Ede would play perfectly with Tiny Core Linux [1] which has FLTK/FLWM as its default desktop system.
Arguably BeOS/Haiku could count too. It’s less obvious later and with experience with Linux stacking WMs, but it was pretty obviously a different lineage at the time.
CUA predates NeXT by quite a lot and so the influence would mostly be going the other way.
CUA was the design paradigm chosen for OS/2, a joint project between IBM and Microsoft. When Microsoft started the Windows Project ( after OS/2 ) they pretty explicitly adopted CUA for it as well.
Last release was 2014. Project is still hosted on SourceForge. Website copyright notice ends in 2018. Last commit to the github repo was 2018. Project front page mentions the original Xbox, Minix, and Zaurus (and early 2000s Japanese handheld organizer that ran Linux) and Solaris as targets.
This should give you some idea of what time frame to view any claims from the website in.
I don't see that as negative, but a remark that most younger people are not used to the look of Windows up to (and including) 2000.
And the last time I personally used FLTK had been around 2000 too. Which, btw, (at least back than) looked more like Irix' 4DWM controls than Windows.
XP, Vista and 7 had a classic look mode. And from w2k's classic look to Vista the interface it's almost identical. Windows 8 and tablet UI's were disruptive.
Just wait. Ten years from now kids will be like, "wait, you can't wear it on your face?? What's a mouse? Why won't this computer just do what I'm thinking? Mom!!!"
Last year I had a "oh, shit, I'm old" moment when I was talking with a 20-something year old who didn't know what a dial tone was. She never used a landline phone.
Neural implants do, too. Particularly the need for a large 1/4" jack in your head. Like, you're telling me you can drill out that much brain meat, but you can't a fit bluetooth chip in there?
I wouldn't put anything after Windows 2000 on the same category as this. And how many people got to be introduced to computers in their teen years via Gnome 2?
Most widgets are the same under a different style, such as the UI from Be and today's Haiku. Even KDE3.
Smartphones and tablets are a different beast altogether.
React OS probably also has the Classic Windows look available. They seem to have switched their main screenshots to something resembling Windows 10, though: https://reactos.org/gallery/
https://spitzak.github.io/