If you need to add a shortcut to your own Firefox menu to perform the addon action, you need to edit extension\content\firebug\firefox\browserMenu.js and add accesskey :
// Firefox page context menu $menupopupOverlay(doc, $(doc, "contentAreaContextMenu"), [ $menuseparator(doc), $menuitem(doc,{ id: "menu_ext", .... accesskey: "s" }) ]);
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