--- a/browser/components/extensions/ext-browserAction.js
+++ b/browser/components/extensions/ext-browserAction.js
@@ -229,18 +229,19 @@ BrowserAction.prototype = {
           }
         }
         break;
 
       case "popupshowing":
         const menu = event.target;
         const trigger = menu.triggerNode;
         const node = window.document.getElementById(this.id);
+        const contexts = ["toolbar-context-menu", "customizationPanelItemContextMenu"];
 
-        if (menu.localName === "menupopup" && node && isAncestorOrSelf(node, trigger)) {
+        if (contexts.includes(menu.id) && node && isAncestorOrSelf(node, trigger)) {
           global.actionContextMenu({
             extension: this.extension,
             onBrowserAction: true,
             menu: menu,
           });
         }
         break;
     }

--- a/browser/components/extensions/ext-pageAction.js
+++ b/browser/components/extensions/ext-pageAction.js
@@ -162,17 +162,17 @@ PageAction.prototype = {
           this.handleClick(window);
         }
         break;
 
       case "popupshowing":
         const menu = event.target;
         const trigger = menu.triggerNode;
 
-        if (menu.localName === "menupopup" && trigger && trigger.id === this.id) {
+        if (menu.id === "toolbar-context-menu" && trigger && trigger.id === this.id) {
           global.actionContextMenu({
             extension: this.extension,
             onPageAction: true,
             menu: menu,
           });
         }
         break;
     }

--- a/browser/components/extensions/test/browser/browser_ext_contextMenus_actionMenus.js
+++ b/browser/components/extensions/test/browser/browser_ext_contextMenus_actionMenus.js
@@ -37,25 +37,28 @@ add_task(function* () {
   const tabId = yield extension.awaitMessage("ready");
 
   for (const kind of ["page", "browser"]) {
     const menu = yield openActionContextMenu(extension, kind);
     const [submenu, second, , , , last, separator] = menu.children;
 
     is(submenu.tagName, "menu", "Correct submenu type");
     is(submenu.label, "parent", "Correct submenu title");
-    is(submenu.firstChild.children.length, 2, "Correct number of submenu items");
+
+    const popup = yield openActionSubmenu(submenu);
+    is(popup, submenu.firstChild, "Correct submenu opened");
+    is(popup.children.length, 2, "Correct number of submenu items");
 
     is(second.tagName, "menuitem", "Second menu item type is correct");
     is(second.label, "click 1", "Second menu item title is correct");
 
     is(last.label, "click 5", "Last menu item title is correct");
     is(separator.tagName, "menuseparator", "Separator after last menu item");
 
-    yield closeActionContextMenu(last);
+    yield closeActionContextMenu(popup.firstChild);
     const {info, tab} = yield extension.awaitMessage("click");
     is(info.pageUrl, "http://example.com/", "Click info pageUrl is correct");
     is(tab.id, tabId, "Click event tab ID is correct");
   }
 
   yield BrowserTestUtils.removeTab(tab);
   yield extension.unload();
 });

--- a/browser/components/extensions/test/browser/head.js
+++ b/browser/components/extensions/test/browser/head.js
@@ -5,17 +5,17 @@
 /* exported CustomizableUI makeWidgetId focusWindow forceGC
  *          getBrowserActionWidget
  *          clickBrowserAction clickPageAction
  *          getBrowserActionPopup getPageActionPopup
  *          closeBrowserAction closePageAction
  *          promisePopupShown promisePopupHidden
  *          openContextMenu closeContextMenu
  *          openExtensionContextMenu closeExtensionContextMenu
- *          openActionContextMenu closeActionContextMenu
+ *          openActionContextMenu openActionSubmenu closeActionContextMenu
  *          imageBuffer getListStyleImage getPanelForNode
  *          awaitExtensionPanel awaitPopupResize
  *          promiseContentDimensions alterContent
  */
 
 const {AppConstants} = Cu.import("resource://gre/modules/AppConstants.jsm");
 const {CustomizableUI} = Cu.import("resource:///modules/CustomizableUI.jsm");
 
@@ -249,16 +249,24 @@ function* openActionContextMenu(extensio
 
   const shown = BrowserTestUtils.waitForEvent(menu, "popupshown");
   EventUtils.synthesizeMouseAtCenter(button, {type: "contextmenu"}, win);
   yield shown;
 
   return menu;
 }
 
+function* openActionSubmenu(submenuItem, win = window) {
+  const submenu = submenuItem.firstChild;
+  const shown = BrowserTestUtils.waitForEvent(submenu, "popupshown");
+  EventUtils.synthesizeMouseAtCenter(submenuItem, {}, win);
+  yield shown;
+  return submenu;
+}
+
 function closeActionContextMenu(itemToSelect, win = window) {
   const menu = win.document.getElementById("toolbar-context-menu");
   const hidden = BrowserTestUtils.waitForEvent(menu, "popuphidden");
   if (itemToSelect) {
     EventUtils.synthesizeMouseAtCenter(itemToSelect, {}, win);
   } else {
     menu.hidePopup();
   }