A high-level look at the project's architecture and a guide to where to find things.
Overview of Comm Central
The following directories are included in the comm-central repository:
Miscellaneous files used by the build process.
Source code of the Lightning extension and Google Calendar Provider extension.
Files for the chat component of Thunderbird. There is also related code in mail/components/im.
The subdirectories are:
components Various chat features, includes the interfaces that each protocol must implement.
content User interface files which become chrome://chat/content/….
locales The user-visible strings, in US English. Files from this directory become chrome://chat/locale/….
protocols Various protocol implementations. Each of subdirectory implements a protocol to the interfaces found under components.
themes Common and platform-specific styling specific to chat. Files from this directory become chrome://chat/skin/….
The LDAP C SDK. Used for communicating with LDAP servers.
Thunderbird specific source code. It's no coincidence that this folder is laid out a lot like the browser and toolkit directories on mozilla-central. Many of the subdirectories follow the same pattern:
content User interface files which become chrome://messenger/content/….