The location of UI elements like the bookmarks, feed and go buttons. Create new image or button child elements to add your own items.
(The URL bar is also known as the Address bar and the Navigation bar.)
Example
The default contents of browser.xul:
<hbox id="urlbar-icons"> <button be="" chromedir="ltr" class="urlbar-icon" click="" for="" id="safebrowsing-urlbar-icon" img="" level="safe" might="" onclick="goDoCommand('safebrowsing-show-warning');" page="" style="-moz-user-focus:" tooltiptext="This" type="menu"> <img class="urlbar-icon" id="star-button" onclick="PlacesStarButton.onClick(event);" /><img address="" chromedir="ltr" class="urlbar-icon" id="go-button" in="" location="" onclick="handleURLBarCommand(event);" p="" the="" to="" tooltiptext="Go" /> </button></hbox>