I use the following code
<menu image="chrome://mecho/content/ic.png" label="Mecho Submission Form" class="menu-iconic" id="mechi-menu" insertafter="context-copylink">
Firefox displays an icon in the menu; however when I use the following (for the submenu)
<menuitem label="App" image="chrome://mecho/content/icons/app.png" class="menu-iconic" onclick="mecho.add('katzcd','App')"/>
It doesn't show up!! any idea?