How to disable ctrl/alt + Key combinations on web applications?

I have a popup window opened in fullscreen mode. But if someone presses the key combinations, ctrl + w or alt + F4 , this popup gets closed without any confirmation. I do not want the users to close the application unless they click a "close button image" .

I also would like to know if there is any easier way to make my web application load fullscreen other than opening that page in a popup window.

Please help me....