Menu bar overlay in Firefox

I tried to overlay an option in the Tools menu of the Firefox menu bar but is not working. Below is the code:

<?xml version="1.0"?>
<?xml-stylesheet href="chrome://linktargetfinder/skin/skin.css" type="text/css"?> 
<!DOCTYPE linktargetfinder SYSTEM "chrome://linktargetfinder/locale/translations.dtd">
<overlay id="sample" xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
    <script src="linkTargetFinder.js" />

    <menupopup id="menu_ToolsPopup"> 
        <menuitem label="&runlinktargetfinder;" key="link-target-finder-run-key" oncommand="linkTargetFinder.run()"/> 
    </menupopup>

    <keyset>
        <key id="link-target-finder-run-key" modifiers="accel alt shift" key="L" oncommand="linkTargetFinder.run()"/>
    </keyset>

    <statusbar id="status-bar">
        <statusbarpanel id="link-target-finder-status-bar-icon" class="statusbarpanel-iconic" src="chrome://linktargetfinder/skin/status-bar.png" tooltiptext="&runlinktargetfinder;" onclick="linkTargetFinder.run()" />
    </statusbar>

    <toolbarpalette id="BrowserToolbarPalette">
        <toolbarbutton id="link-target-finder-toolbar-button" label="Link Target Finder" tooltiptext="&runlinktargetfinder;" oncommand="linkTargetFinder.run()"/>
    </toolbarpalette>
</overlay&g开发者_如何学运维t;

But it is not appearing.Blow is my chrome.manifest file.Please help.

content     linktargetfinder    chrome/content/
content     linktargetfinder    chrome/content/ contentaccessible=yes
overlay chrome://browser/content/browser.xul chrome://linktargetfinder/content/browser.xul

locale  linktargetfinder    en-US   locale/en-US/

skin    linktargetfinder    classic/1.0 skin/
style   chrome://global/content/customizeToolbar.xul    chrome://linktargetfinder/skin/skin.css

overlay chrome://browser/content/browser.xul chrome://linktargetfinder/content/browserOverlay.xul

or

overlay chrome://browser/content/browser.xul chrome://linktargetfinder/content/overlay.xul

Try any one of these in your chrome.manifestfile. And the rest everything is fine in your file.