Rated 5 out of 5 stars

SUGGESTION: add a hotkey so the menu can be opened in fullscreen mode. Here's some XUL code additions that will do it:
<commandset id="mainCommandSet">
<command id="cmd_mainMenuPopper" oncommand="if (window.fullScreen) {document.getElementById('appmenu-popup').openPopupAtScreen(0,0,true);} else {document.getElementById('appmenu-popup').openPopup(document.getElementById('appmenu-button'),'after_start',0,0,false,false);}"/>
</commandset>
<keyset id="mainKeyset">
<key id="key_menu_popper" modifiers="alt" key="`" oncommand="document.getElementById('cmd_mainMenuPopper').doCommand();"/>
</keyset><button id="appmenu-button" type="" command="cmd_mainMenuPopper"/>
<script>
<![CDATA[ (function () { document.getElementById('main-window').insertBefore(document.getElementById('appmenu-popup'), document.getElementById('titlebar')); })(); ]]>
</script>

This was just a quick and dirty change for my use, so it defines Alt - ` to pop open the menu; but you can change that or even put in an option to define it.

This review is for a previous version of the add-on (4.3.2).  This user has 3 previous reviews of this add-on.

I'm not sure whether the missing Firefox Button will be brought back or not in the final version of Firefox.If not, I will try to make a workaround about it in the new version.