Window decorator has a specific meaning in X terminology, referring to the frame of the window done by the window manager. The screenshots are using some comme

Window decorator has a specific meaning in X terminology, referring to the frame of the window done by the window manager. The screenshots are using some commercial Unix wm (mwm?) or one of the free ones that copies their look (fvwm?) I use fvwm on one of my machines in 2023, in part because I found myself on a retro kick a few years ago, so I don't think it's that weird, though it is extremely dated.