On some websites they have directory listing like this:

www.example.com/demowebsite/

and nothing else?!But visitors can preview all pages,all buttons...all but can not see the code or images.In all preview pages are same directory,without changes,like in the example above!

How they do that??? Are they doing that in Flash,PHP or some another way???

@46Bit

I know how to protect my design with watermarks but I want to do that in some different way,like in the example above.I hope you understand what I have in my mind. Anyway thanks for the reply 46Bit.