Well, you opened the can of worms with that comment.
The overall point is to create minimalist windows that have titles that can be listed.
I'm exploring this subthread because Peter suggested that the Custom HTML Prompt action could be used, but I had initial trouble listing those windows because, being owned by the KBM Engine, they were overlooked because the Engine was "background only". Your help in this subthread seems to have handled that.
To complete that idea, I still need to try creating Custom HTML Prompt windows, giving them custom titles, and listing them as you just described, to fully test this option.
The larger context of why I want the minimalist windows is to use them as Desktop Workspace Identifiers (DTWSID) to put one on every Desktop Workspace so there is a text name that stays with the Desktop even if I rearrange their order in Mission Control, or even if Mission Control gets set to rearrange them automatically. I have multiple threads I am exploring to see how I might be able to make useful DTWSIDs.
Listing all those app windows' titles gives me a list of Desktop Workspace names so that, simply by activating that named window, I switch to that desired Desktop as the active Desktop Workspace.
This minimalist window approach is one route I am exploring. I am also looking at having a floating Notes window on each Desktop, a TextEdit window, and a couple of other free apps that have been around for years, Text Do and Folding Text, or maybe a flexible combination of all of them at once.
The key is that Text Do and Folding Text also behave like Notes and TextEdit when rebooting (if I don't close the app first), they reopen all their previous windows in their original desktops. (I had previously tried Stickies, but Stickies reopen all in the first desktop and having to move 20 Stickies to their respective Desktops repeatedly, quickly became annoying.) I don't know yet if KBM's Custom HTML Prompt can be made to work like this.
All this is because I have become addicted to named Desktops and I see repeatedly in various Stack Exchange and Apple forums that many people are as chronically dissatisfied as I am with Apple's lack of support for Desktops. I would love to be able to recommend my solution. But I can't.
I have been able to name my desktops by using CurrentKey, which I have learned uses this same approach as I have outlined above, he hides a thin app window behind the Menu Bar with a window title that is the name of the desktop and then activates that window to change desktops. But CurrentKey has been withdrawn for various reasons. So I can't offer it as a solution.
I've been exploring the question of whether I could imitate the named desktop switching of CurrentKey by using KBM and AppleScript, etc. So far, the answer is that it is not impossible.