Customizing Firefox

Continuing with Firefox our next assignment was to modify the browser slightly by making new tabs appear right after the current tab. Since we already know how to get the source code and build it it's just a matter of finding the code we need to modify.

One way of searching through the code is to use http://mxr.mozilla.org.

We eventually found our way to this snippet of code: http://mxr.mozilla.org/mozilla-central/source/browser/base/content/tabbrowser.xml#1326

             // Check if we're opening a tab related to the current tab and
             // move it to after the current tab.
             // aReferrerURI is null or undefined if the tab is opened from
             // an external application or bookmark, i.e. somewhere other
             // than the current tab.
             if ((aRelatedToCurrent == null ? aReferrerURI : aRelatedToCurrent) &&
                 Services.prefs.getBoolPref("browser.tabs.insertRelatedAfterCurrent")) {
               let newTabPos = (this._lastRelatedTab ||
                                this.selectedTab)._tPos + 1;
               if (this._lastRelatedTab)
                 this._lastRelatedTab.owner = null;
               else
                 t.owner = this.selectedTab;
               this.moveTabTo(t, newTabPos);
               this._lastRelatedTab = t;
             }

Just by reading the commented code you'll see that this is exactly what we're looking for. It checks to see if the current tab is related to the new tab and will open it next to the current if true. So by commenting out the first "if" statement we will essentially make all new tabs open next to the current. Our new changes will look like this:

-            if ((aRelatedToCurrent == null ? aReferrerURI : aRelatedToCurrent) &&
-                Services.prefs.getBoolPref("browser.tabs.insertRelatedAfterCurrent")) {
+            //if ((aRelatedToCurrent == null ? aReferrerURI : aRelatedToCurrent) &&
+            //    Services.prefs.getBoolPref("browser.tabs.insertRelatedAfterCurrent")) {
               let newTabPos = (this._lastRelatedTab ||
                                this.selectedTab)._tPos + 1;
               if (this._lastRelatedTab)
                 this._lastRelatedTab.owner = null;
               else
                 t.owner = this.selectedTab;
               this.moveTabTo(t, newTabPos);
               this._lastRelatedTab = t;
-            }
+            //}

Thats it, we didn't even have to write any new code, simply commenting out several lines did what we were looking for. Finally build the source code again.