Old question, Embed javascript extension

Hey all,

I have a questions about javascript extension after you embeding the
xulrunner.

so far, i found that if you want to write a extension to the
javascript, u have to create a component, isn't it?

Is there any easy way to do it?

For example: in the IE, there is document.external, which u can simply
provide a javascript extension from c++ code.

secondly, i am new to xulrunner, i found it's hard to execute a
javascript code from C++, any directions?

Thirdly, if I want to save the current page view as a picture, which
interface should I use? any direction?

Thanks!

Cheers.