It can be nice to access your FF extension's variables/functions from the browser console (ctrl+shift+j) if you need some insight into its state.

It took me a while to figure this out, so I'm sharing it. Somewhere in your extension, do:

var chromewin = win_util.getMostRecentBrowserWindow();
chromewin.my_extension_state = ...;

Now in the browser console, you can access whatever variables you set in the global variable my_extension_state. In my case, I used it to assign a function that lets me evaluate code in the addon's background page. This lets me gain insight into the background page's variables and state straight from the browser console.

Note! This is a security hole. Only enable this when debugging your extension/addon. Disable it when you release it.