Intercepting and replacing page-level HTTP requests with custom extension-made responses?

Question

I am making a firefox extension which injects most of its interface in the pages. However, if I want images in that interface, I am unable to inject them. So what I am trying is to intercept specific http requests and replace them with the local images. So far I have been able to intercept specific pages and replace them with others, but I am not able to replace just an image. Any ideas?

Answer 1

Did you try out the observe "http-on-modify-request" or "http-on-modify-request" methods? I'm having issues with these API's as well.