How to change configurations in the old development environment

Add-ons Development
#1

I am aware that I can not change the configurations in the new development environment (webextension). For purpose of testing, I need to do that even in the deprecated development environemnt. If this is possible, can you provide me with some helpful links?

#2

With the Add-On SDK

const { Services } = require('resource://gre/modules/Services.jsm');
const browserPrefs = Services.prefs.getBranch('browser.');
const maxTabsUndo = browserPrefs.getIntPref('sessionstore.max_tabs_undo');

And if you don’t have access to require, use

Components.utils.import("resource://gre/modules/Services.jsm"); /* global Services */