Wladimir Palant’s great post about using namespaces in XUL overlays gives me another chance to explain one aspect of Firebug source that throws some folks off at first All the Firebug source files have the following construct: FBL.ns(function() { with (FBL) {const Cc = Components.classes; const Ci = Components.interfaces; ...more constants...

Firebug.Debugger = ......more code..}}); What’s that stuff about? Well [...]