Real World Mozilla Source Code Reading Lab

I got my first hand experience on searching and reading Mozilla code using the mozilla cross reference website with the tool - sea monkey. I find this application to be very useful in finding ANY type of source code or functions that is available. My first attempt was to research how the Stop button for a browser would work. As a first timer, I trailed off and found the cancel button to stop file downloads. I thought it was the same concept using the same class but it actually wasn't as Dave (professor) told me. I continued to search for the correct one but it is harder then i thought it would be. You have to dig through a lot of code to find the source!