At the moment not many, but full-screen layout support is planned. The eventual "end-state" of the framework would be something along the lines of MC, where there is a main, fullscreen display that contains a bunch of inner elements. These inner elements would then create modal windows, allows user input and display data as needed. Only difference from MC and the like is in this case the windows aren't just things that look like windows, but they actually act and behave like it too.

Fair question though! WindowManager honestly started off as a joke with my friend, and just so happened to end up being the main "entry point" to the library. In the future pre-defined (or even dynamic) layouts should allow the above mentioned to happen when needed, but also keep all the optional mouse input shenanigans working as intended.

Edit: One thing that I think can showcase some of the upsides an architecture like this has is an ongoing project of mine based on PTG, https://github.com/bczsalba/Pagoda. It is primarily a frontend for a WIP messaging protocol me an my friend are creating, but the main idea behind it is the chat functionality is all confined within an "application", and that the user can write and install their own applications to be run from within Pagoda. This kind of makes the system feel like a proper desktop WM, and I think is a really cool idea. As the project is still very early the only available app is the messaging one, but I do have high hopes for it, if nothing else as a tech-demo for what PTG can do.