I think this could also work as a background .fla "module" which could also read the config and load a background .jpg
I still see the lack of any link in the main menu that will take you back to the start page apart from making it yourself in the sitemenu.ini, i can understand if the start page was intended as an intro page etc but what if you was able to load code into the start page so people could design their own mini-site, maybe then you could have a links page instead of it being a popup!
Even if it was just a formated .txt page or a simple html, people could even then include something like a blog into the start page. You could have the files layed out like the the way the gallery files are in sub folders, /pages/page1/ containing the .html/.txt and any images that page would need..