For example, can I start an instance of "Calculator.exe" on the user's computer (if it is available of course) upon some particular event in firefox, say clicking of a button?

I thought of perhaps linking the extension to Python's subprocess method using XPCOM. But I was wondering whether there is an easier way.

Additional information: I do not, at this point need to interact with the application upon its instantiation. Therefore I am looking for a way to open an application that's all.

(Though, out of interest, if you have any pointers to interact with the same as well, that would be great)

Thanks!