Bug 708640 Should be able to open a new tab by middle-clicking the "Go" button r=Neil.

suite/browser/navigator.js

@@ -1608,7 +1608,8 @@ function handleURLBarCommand(aUserAction, aTriggeringEvent)
     // Accept both Control and Meta (=Command) as New-Window-Modifiers
     if (aTriggeringEvent &&
         (('ctrlKey' in aTriggeringEvent && aTriggeringEvent.ctrlKey) ||
-         ('metaKey' in aTriggeringEvent && aTriggeringEvent.metaKey))) {
+         ('metaKey' in aTriggeringEvent && aTriggeringEvent.metaKey) ||
+         ('button'  in aTriggeringEvent && aTriggeringEvent.button == 1))) {
       // Check if user requests Tabs instead of windows
       if (GetBoolPref("browser.tabs.opentabfor.urlbar", false)) {
         // Open link in new tab

suite/browser/navigator.xul

@@ -347,6 +347,7 @@
                 tooltiptext="&goButton.tooltip;"
                 default="true"
                 oncommand="handleURLBarCommand('none', event);"
+                onclick="checkForMiddleClick(this, event);"
                 ondragover="nsDragAndDrop.dragOver(event, goButtonObserver);"
                 ondragdrop="nsDragAndDrop.drop(event, goButtonObserver);"
                 ondragexit="nsDragAndDrop.dragExit(event, goButtonObserver);"/>