javascript - Display 'Hello World' with a Firefox extension -

does know of way display 'hello world' in blank page when user of firefox opens new tab (with extension) ?

use on xul file:

gbrowser.addeventlistener("domcontentloaded",     function(e) {         var contentwindow = e.originaltarget.defaultview;          contentwindow//.getelementbyid, tagname, etc...      }, false); 

contentwindow wrapped window of tab.

for raw window (same window if type script on address bar) see this.