I'm trying to debug a Firefox extension, using Firefox 28.0.
I have set up the dev environment as suggested in https://developer.mozilla.org/en-US/Add-ons/Setting_up_extension_development_environment (actually I just took the lazy way out and installed the DevPrefs extension to set all the necessary about:configs)
I then open Firefox and go into the debugging environment (Tools > Web Developer > Browser Toolbox).
I then go to the Debugger tab.
However, under the Sources pane, under my extension (e.g. chrome://myextension), I only see some of the JS and XUL files that are contained in my extension XPI.
How can I manually "load files" in the debugger, so that I can set a breakpoint and trace the runtime of my extension?