Re: [RESOLVED] Dropdown Box
Headers get sent before PHP script runs if there is something before the PHP script starts running, ie. " <?php ... ?>" (without the quotes) prepares and sends the headers, because there is a space character, sendable page content, before the script. If you start with a script right away, then nothing gets sent and you can do to headers whatever you wish. But if you do echo, then you'll again send headers and you can't change headers anymore, because you've sent page content.
So long story short, you can change and add headers as long as you don't send any data to the client.