A very simple equivalent to Tree Style Tab firefox extension. Without very back hacks like .toSource().replace(...,...), nor firefox functions overload, ...

Highlight addon-sdk capabilities and how to hack firefox like a gentleman.

You need to patch SDK 1.0rc2 to make it work. Open "packages/api-utils/content/content-proxy.js" and replace last function definition with this:

exports.create = function create(object) { let xpcWrapper = XPCNativeWrapper(object); if (xpcWrapper === object) return object; return getProxyForObject(xpcWrapper); }