The PHP-Nuke HTML header (i.e. everything that goes between the <head> and </head> tags in the HTML code of the generated page) is fully customizable
popup windows, etc. With this file you don't need to edit system code each time you upgrade to a new version. Just remember, in case you add code here to not overwrite this file when updating!
Whatever you put here will be between <head> and </head> tags.
Here are some example customizations of the PHP-Nuke HTML header: