I had to create an extension for contacts import into Thunderbird. This part is done, now I need to import tasks. But tasks/calendar are not handled by default in thunderbird, so I need Lightning. Here is my problem. I have no idea if I can detect an other extension and use some of its features.
Easiest way to detect Lightning is checking whether its interfaces are defined, e.g.:
if ("calICalendar" in Components.interfaces)
alert("Lightning is installed!");
Using its features is a different thing - depends on what you are trying to do. For most things importing Lightning's modules and using them should do:
I don't think it is properly documented however, you will have to look at the source code.