--- a/browser/components/customizableui/content/panelUI.js
+++ b/browser/components/customizableui/content/panelUI.js
@@ -677,18 +677,24 @@ const PanelUI = {
       // since we don't want their doorhangers competing for attention
       doorhangers.forEach(n => { n.dismissed = true; })
       this._hidePopup();
       this._clearBadge();
       if (!this.notifications[0].options.badgeOnly) {
         this._showMenuItem(this.notifications[0]);
       }
     } else if (doorhangers.length > 0) {
-      this._clearBadge();
-      this._showNotificationPanel(doorhangers[0]);
+      if (window.fullScreen) {
+        this._hidePopup();
+        this._showBadge(doorhangers[0]);
+        this._showMenuItem(doorhangers[0]);
+      } else {
+        this._clearBadge();
+        this._showNotificationPanel(doorhangers[0]);
+      }
     } else {
       this._hidePopup();
       this._showBadge(this.notifications[0]);
       this._showMenuItem(this.notifications[0]);
     }
   },
 
   _showNotificationPanel(notification) {

--- a/browser/components/customizableui/test/browser_panelUINotifications.js
+++ b/browser/components/customizableui/test/browser_panelUINotifications.js
@@ -298,8 +298,47 @@ add_task(function* testMultipleNonBadges
     isnot(PanelUI.menuButton.getAttribute("badge-status"), "update-manual", "update-manual badge is hidden on PanelUI button.");
     menuItem = doc.getElementById("PanelUI-update-manual-menu-item");
     is(menuItem.hidden, false, "update-manual menu item is showing.");
 
     menuItem.click();
     ok(updateManualAction.called, "update-manual main action callback was called");
   });
 });
+
+add_task(function* testFullscreen() {
+  let doc = document;
+
+  is(PanelUI.notificationPanel.state, "closed", "update-manual doorhanger is closed.");
+  let mainActionCalled = false;
+  let mainAction = {
+    callback: () => { mainActionCalled = true; }
+  };
+  PanelUI.showNotification("update-manual", mainAction);
+
+  isnot(PanelUI.notificationPanel.state, "closed", "update-manual doorhanger is showing.");
+  let notifications = [...PanelUI.notificationPanel.children].filter(n => !n.hidden);
+  is(notifications.length, 1, "PanelUI doorhanger is only displaying one notification.");
+  let doorhanger = notifications[0];
+  is(doorhanger.id, "PanelUI-update-manual-notification", "PanelUI is displaying the update-manual notification.");
+
+  let popuphiddenPromise = BrowserTestUtils.waitForEvent(PanelUI.notificationPanel, "popuphidden");
+  EventUtils.synthesizeKey("VK_F11", {});
+  yield popuphiddenPromise;
+  yield new Promise(executeSoon);
+  is(PanelUI.notificationPanel.state, "closed", "update-manual doorhanger is closed.");
+
+  window.FullScreen.showNavToolbox();
+  is(PanelUI.menuButton.getAttribute("badge-status"), "update-manual", "Badge is displaying on PanelUI button.");
+
+  let popupshownPromise = BrowserTestUtils.waitForEvent(PanelUI.notificationPanel, "popupshown");
+  EventUtils.synthesizeKey("VK_F11", {});
+  yield popupshownPromise;
+  yield new Promise(executeSoon);
+  isnot(PanelUI.notificationPanel.state, "closed", "update-manual doorhanger is showing.");
+  isnot(PanelUI.menuButton.getAttribute("badge-status"), "update-manual", "Badge is not displaying on PanelUI button.");
+
+  let mainActionButton = doc.getAnonymousElementByAttribute(doorhanger, "anonid", "button");
+  mainActionButton.click();
+  ok(mainActionCalled, "Main action callback was called");
+  is(PanelUI.notificationPanel.state, "closed", "update-manual doorhanger is closed.");
+  is(PanelUI.menuButton.hasAttribute("badge-status"), false, "Should not have a badge status");
+});