How can I debug a Firefox extension with Firebug?

Question

I'm trying to use Firebug to debug a JavaScript file in an extension I've added to Fx 4.
Can anyone tell me how to do it? I can only see website scripts.

Answer 1

Use Chromebug it's firebug for extension development, witch will give you the full ability to inspect debug firefox it self and all firefox extension as if it's a webpage :)

1- install the latest version from here: http://getfirebug.com/releases/chromebug/

2- Winkey+R to open run then type firefox.exe -chromebug this will run firefox with chromebug

3- for more information visit http://getfirebug.com/wiki/index.php/Chromebug

Answer 2

Please see MDN - Building An Extension - Debugging Extensions, which shows what tools Firefox provides you with to natively debug extension, also take a look at Dive Into Greasemonkey - Debugging User Scripts (PDF, p.13) which is aimed more specifically at your request.

Other than that, see How to debug a Greasemonkey script with the Firebug extension?