Great to see Skyscrapersim back in development! I've played around a little with the Alpha 11 release; here's some feedback on what I've discovered.
Upon loading, I immediately noticed the FPS counter in the top right-hand corner. I know you can disable it with F9, but would it be possible to make this an option in the INI file to save it being done every time a building is loaded?

From what I've seen, the experimental lighting engine works well. The lights give off a good effect, but I can see it is experimental.
Using Point Lights, I attempted to making some exterior lights on a lift light up, but the light went through walls onto the other shaft:

Hypothetically, this is how I would (somewhat) expect it to work:

For reference, this is how the lifts look when there are none present and turned off in the INI, respectively:


Also, when lighting is enabled, this error is thrown every time the building is reloaded using Ctrl+R. After pressing OK, the building still loads fine, it's just that the error appears every time.

Otherwise, the sim looks looks as good as ever!