--- a/browser/components/customizableui/CustomizableUI.jsm
+++ b/browser/components/customizableui/CustomizableUI.jsm
@@ -1803,39 +1803,23 @@ var CustomizableUIInternal = {
     }
 
     // We can't use event.target because we might have passed a panelview
     // anonymous content boundary as well, and so target points to the
     // panelmultiview in that case. Unfortunately, this means we get
     // anonymous child nodes instead of the real ones, so looking for the
     // 'stoooop, don't close me' attributes is more involved.
     let target = aEvent.originalTarget;
-    let closemenu = "auto";
-    let widgetType = "button";
     while (target.parentNode && target.localName != "panel") {
-      closemenu = target.getAttribute("closemenu");
-      widgetType = target.getAttribute("widget-type");
-      if (closemenu == "none" || closemenu == "single" ||
-          widgetType == "view") {
-        break;
+      if (target.getAttribute("closemenu") == "none" ||
+          target.getAttribute("widget-type") == "view") {
+        return;
       }
       target = target.parentNode;
     }
-    if (closemenu == "none" || widgetType == "view") {
-      return;
-    }
-
-    if (closemenu == "single") {
-      let panel = this._getPanelForNode(target);
-      let multiview = panel.querySelector("panelmultiview");
-      if (multiview.showingSubView) {
-        multiview.goBack();
-        return;
-      }
-    }
 
     // If we get here, we can actually hide the popup:
     this.hidePanelForNode(aEvent.target);
   },
 
   getUnusedWidgets(aWindowPalette) {
     let window = aWindowPalette.ownerGlobal;
     let isWindowPrivate = PrivateBrowsingUtils.isWindowPrivate(window);

--- a/browser/components/customizableui/PanelMultiView.jsm
+++ b/browser/components/customizableui/PanelMultiView.jsm
@@ -375,20 +375,16 @@ var PanelMultiView = class extends this.
 
   get _screenManager() {
     if (this.__screenManager)
       return this.__screenManager;
     return this.__screenManager = Cc["@mozilla.org/gfx/screenmanager;1"]
                                     .getService(Ci.nsIScreenManager);
   }
 
-  get showingSubView() {
-    return this.openViews.length > 1;
-  }
-
   constructor(node) {
     super(node);
     this._openPopupPromise = Promise.resolve(false);
     this._openPopupCancelCallback = () => {};
   }
 
   connect() {
     this.connected = true;
@@ -434,22 +430,16 @@ var PanelMultiView = class extends this.
     // Proxy these public properties and methods, as used elsewhere by various
     // parts of the browser, to this instance.
     ["goBack", "showSubView"].forEach(method => {
       Object.defineProperty(this.node, method, {
         enumerable: true,
         value: (...args) => this[method](...args)
       });
     });
-    ["showingSubView"].forEach(property => {
-      Object.defineProperty(this.node, property, {
-        enumerable: true,
-        get: () => this[property]
-      });
-    });
   }
 
   disconnect() {
     // Guard against re-entrancy.
     if (!this.node || !this.connected)
       return;
 
     this._cleanupTransitionPhase();