Skype uses Qt, not Mozilla: http://www.google.com/search?hl=en&q=skype+qt&btnG=Google+Search http://www.google.com/search?hl=en&q=skype+qt&btnG=Google+Search I

Skype uses Qt, not Mozilla: http://www.google.com/search?hl=en&q=skype+qt&btnG=Google+Search http://www.google.com/search?hl=en&q=skype+qt&btnG=Google+Search I agree that a Javascript-based client-app might not perform as well as a native C/C++ app, but I would not say "could never be developed"... Adobe Apollo does generate a compiled package (aka "air"). I believe Apollo also generates a native executable file after the app is installed. PS: I'm not an Apollo evangelist. I just wanted to point out that web-based client apps are not about off-line features.