root/lang/javascript/userchrome/AddonsDownloadsSidebar.uc.xul

<?xml version="1.0"?>
<overlay id="AddonsDownloadsSidebar"
      xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
  <!-- show add-ons and downloads in sidebar-->
        <broadcasterset id="mainBroadcasterSet">
                <broadcaster id="viewAddonsSidebar" autoCheck="false" label="Add-ons" type="checkbox" group="sidebar" sidebarurl="chrome://mozapps/content/extensions/extensions.xul" sidebartitle="Add-ons" oncommand="toggleSidebar('viewAddonsSidebar');"/>
                <broadcaster id="viewDownloadsSidebar" autoCheck="false" label="Downloads" type="checkbox" group="sidebar" sidebarurl="chrome://mozapps/content/downloads/downloads.xul" sidebartitle="Downloads" oncommand="toggleSidebar('viewDownloadsSidebar');"/>
        </broadcasterset>

        <menupopup id="viewSidebarMenu">
                <menuitem key="addons-view-sidebar" observes="viewAddonsSidebar"/>
                <menuitem key="downloads-view-sidebar" observes="viewDownloadsSidebar"/>
        </menupopup>

        <script type="application/x-javascript" xmlns="http://www.w3.org/1999/xhtml"> 
        <![CDATA[
        var menu = document.getElementById("menu_openAddons");
        if(menu) {
                menu.setAttribute("oncommand", "toggleSidebar('viewAddonsSidebar');");
                menu.removeAttribute("command");
        }
        var menu = document.getElementById("menu_openDownloads");
        if(menu) {
                menu.setAttribute("oncommand", "toggleSidebar('viewDownloadsSidebar');");
                menu.removeAttribute("command");
        }
        ]]>
        </script>

</overlay>