This project aims to be a tool, which can help create UI designs/screens for application/web prototyping

My wife is a UX designer. I told her about your project, will let you know here how she likes it :)

Thanks a lot! It's still in development, I will try to target Linux/Windows at first. If it will be possible to test in on OS X, I will be glad to hear reviews from here, because I don't have a machine and cannot test it. Any opinion is valuable :)