For anyone who does not know yet, STLWRT is the successor to GTK+ 2, originally based almost entirely on the original code from GTK+ 2. STLWRT has deviated from the GTK+ 2 code, however, and continues to deviate. Ultimately, the goal is to be able to run most GTK+ 2 and many GTK+ 3 applications using the same STLWRT library, while both types of applications keep a conservative, traditional GTK+ 2-esque look and feel.
I emphasized the word "the" above because, as of right now, I do not know of anyone else who has any actively maintained fork of any version of GTK. If anyone who has such a fork happens to be reading this, please drop me a line and let me know; I'd be interested in the design decisions you are making and have made, and I hope we may be able to collaborate somehow.
Due to a slew of reasons, including personal issues that indirectly involve current events, I cannot commit any more time to open-source in the near term. I am sorry to say this, but therefore, development of this project has stalled and will remain stalled likely for a few more months.
I also believe that when I return to this project, I should probably go about it in a totally different way. I might even have to rebase STLWRT off of GTK+ 2.32.32 or 2.32.33 all over again. If that is the case, then this repository will be permanently suspended, and I will then begin working on STLWRT-ng or whatever it may be named. However, that does not mean that that is the definite fate of STLWRT.
Do not keep posing issues about how to compile STLWRT; I will not respond to them anymore, at least in this repository.