Let Firefox listens to my order

I was breaking the source code of Firefox last night. It was assigned by Dave. All I need to do is changing the code of Firefox, and let it directs to the homepage while it opens a new tab. Since I forgot the exactly filenames of source code for how to create a new tab, I have to search their location again.

Beginning
I targeted on the navigator bar because it has the new tab button and the home button, which creates a new tab and opens the homepage. Then I went to mxr and searched the label of new tab button, "Open a new tab". follow that was searching, searching and searching.

Found the place
I don't remember how long I spent to find the right place. There are two critical files:
\browser\base\content\tabbrowser.xml line 1256
\browser\base\content\browser.js line 1720
the function addTab() inside the first file response open a new tab. the function gHomeButton.getHomePage() in the second file return the url of homepage.

What I changed
What I changed is I put two lines inside tabbrowser.xml
 
  if(!aURI)
   aURI = gHomeButton.getHomePage();

before

  var blank = !aURI || (aURI == "about:blank");

then, I built the Firefox, and it works.(actually, I built 6 times last night to reach this T_T )

Concision
It is a great experience to modify such a huge open source project. Although it is not much work to do, it still prove I have the ability, possibility and permission to do what I want to do.
BTW, I am read the post from G-Lewis and Scott Downe. They also have a very good post and they remind me I also need to enable the user to optionally set the tab to open homepage or to remain with blank page. Maybe I will try to accomplish that later.