This is great, using actual CDE is abysmal. I didnt get very far installing CDE, but I remember WindowMaker not recognizing full screen YouTube videos, I wouldn’t be he surprised if CDE was the same.
CDE rose out of HP Vue window manager.
Motif was considered to be a good choice; some say it is easy to program.
I was always a little upset when Gtk took off in the late 90s, because it had a bunch of similar pointer abuse. It seemed to be heavily influenced by Motif. Qt seemed much better at the time. Java UI (Swing) clearly seemed a big step forward at the time. Tk was pretty nice at the time.
A lot of the X stack back then had this kind of stuff. At some point it probably got cleaned up.
Not sure how IBM fared but I think HP-UX had it for longer until they dropped it in 11i
It's very telling that no one at Sun would look at OpenLook and recognize it as ugly. Sun was an engineering company, the entire company, from the CEO on down, had no taste.
Exhibit #2: the Java Metal look and feel, almost repulsively ugly, yet no one at Sun saw anything wrong.
Straight window managers require a lot more tinkering and have steeper learning curves.
I'm using Window Maker for years now and full screen YouTube videos work perfectly fine. Perhaps you used some very ancient version? The latest from the official site[0] should work (though getting the "next" branch from git might be better if you want all the latest fixes - and bugs :-P - as releases happen infrequently).
However AFAIK that was in the CRM fork which became the main/official version somewhere in 2013 so it is possible your distro at the time had some version from 2006 (which AFAIK was when the last version from the previous developers was made).
Edit: But now that I think of it, I do remember Motif WM having the same issue with fullscreen, so it's likely CDE does as well.