You don't need a GUI.
There are several ways to get your code running:
- Create a bootstrapped (restartless) add-on, just like
ReDisposition
(The GUI parts there are not required) and register from yourbootstrap.js
. - Create an SDK add-on and register from your
main.js
. - Create an XPCOM component and register it for
profile-after-change
(run at startup, basically) and register once the component gets loaded. - Or have a stub overlay, that will just load a JS code module and register in the module. (A little hackish for my taste, but anyway).
Anyway, in the end, you'll need to register and observe http-examine-response
and friends, no matter what method you use, or what
See MDN for more documentation (and the firefox-addon wiki).
Other than that, your question is too broad to tell you something less general.