I was able to get a snapshot of the Skyscraper source code from March 2007 built and running, so you can try it out if you'd like. This build is of the C++ version, so it's the same app that you're currently using, just very early on, and also using the Crystal Space 1.2 graphics engine. The reason I chose March 2007 for the code, is that I had shown a demonstration in-person of the Glass Tower model to the person who designed the model at that time.
The C++ version had been in development for about a year and a half at this point (it took a while since I was learning C++ as I went along). This was also before I split the sim engine out to a separate DLL file (SBS.dll).
Build:
https://download.skyscrapersim.net/archive/rebuild/skyscraper-mar2007.zipSource code:
https://download.skyscrapersim.net/archive/rebuild/skyscraper-mar2007-src.zipBuilding it was pretty complicated because it needed to be done on a Windows 7 system with the old Visual Studio 2005 compiler. I also used wxWidgets 2.8, and Crystal Space 1.2 with it's dependency addon.