I don't think these ever made it out the door. There's some info/code in the Commodore server dump that was circulating a year or two ago. The build of appshell.library in that archive is dated May 13, 1992, so I think this was something that CATS canceled, as opposed to it being ended by the bankruptcy. There's also an older release notes file (May 1991) that makes reference to appshell.library, appobjects.library, prefs.library, and hyper.library.
I was super-curious about these dev tools also. I asked around at the Amiga 30th in Mountain View in 2015, and if I remember right, I actually got to speak to Randell Jesup and Carolyn Scheppner (and soon after meet Dave Needle). I don't remember if I got to speak with David Junod!
This was all connected & related to an IFF spec that described UI elements using 32-bit words, similar to classic Mac resource forks, no?
PowerWindows (as mentioned later in this thread) from Inovatronics was (IIRC) written by Todor Fay, and is also a big part of how Bars & Pipes UI was constructed.
