--- a/browser/components/customizableui/PanelMultiView.jsm
+++ b/browser/components/customizableui/PanelMultiView.jsm
@@ -282,17 +282,17 @@ this.PanelMultiView = class extends this
                                     .getService(Ci.nsIScreenManager);
   }
   /**
    * @return {panelview} the currently visible subview OR the subview that is
    *                     about to be shown whilst a 'ViewShowing' event is being
    *                     dispatched.
    */
   get current() {
-    return this.node && (this._viewShowing || this._currentSubView);
+    return this.node && this._currentSubView;
   }
   get _currentSubView() {
     // Peek the top of the stack, but fall back to the main view if the list of
     // opened views is currently empty.
     let panelView = this.openViews[this.openViews.length - 1];
     return (panelView && panelView.node) || this._mainView;
   }
 
@@ -592,18 +592,16 @@ this.PanelMultiView = class extends this
   hideAllViewsExcept(nextPanelView = null) {
     for (let panelView of this.knownViews) {
       // When the panelview was already reparented, don't interfere any more.
       if (panelView == nextPanelView || !this.node || panelView.node.panelMultiView != this.node)
         continue;
       panelView.current = false;
     }
 
-    this._viewShowing = null;
-
     if (!this.node || !nextPanelView)
       return;
 
     if (!this.openViews.includes(nextPanelView))
       this.openViews.push(nextPanelView);
 
     nextPanelView.current = true;
     this.showingSubView = nextPanelView.node.id != this._mainViewId;
@@ -617,25 +615,30 @@ this.PanelMultiView = class extends this
       viewNode.panelMultiView = this.node;
 
       let previousViewNode = previousView || this._currentSubView;
 
       if (viewNode.parentNode != this._viewStack) {
         this._viewStack.appendChild(viewNode);
       }
 
+      // Emit the ViewShowing event so that the widget definition has a chance
+      // to lazily populate the subview with things or perhaps even cancel this
+      // whole operation.
+      if (await nextPanelView.dispatchAsyncEvent("ViewShowing")) {
+        return false;
+      }
+
       // If the panelview to show is the same as the previous one, the 'ViewShowing'
       // event has already been dispatched. Don't do it twice.
       let showingSameView = viewNode == previousViewNode;
 
       let prevPanelView = PanelView.forNode(previousViewNode);
       prevPanelView.captureKnownSize();
 
-      this._viewShowing = viewNode;
-
       let reverse = !!previousView;
       if (!reverse) {
         // We are opening a new view, either because we are navigating forward
         // or because we are showing the main view. Some properties of the view
         // may vary between panels, so we make sure to update them every time.
         // Firstly, make sure that the header matches how the view was opened.
         nextPanelView.headerText = viewNode.getAttribute("title") ||
                                    (anchor && anchor.getAttribute("label"));
@@ -645,26 +648,16 @@ this.PanelMultiView = class extends this
         // The constrained width of subviews may also vary between panels.
         nextPanelView.minMaxWidth = isMainView ? 0 : prevPanelView.knownWidth;
       }
 
       if (anchor) {
         viewNode.classList.add("PanelUI-subView");
       }
 
-      if (!showingSameView || !viewNode.hasAttribute("current")) {
-        // Emit the ViewShowing event so that the widget definition has a chance
-        // to lazily populate the subview with things or perhaps even cancel this
-        // whole operation.
-        if (await nextPanelView.dispatchAsyncEvent("ViewShowing")) {
-          this._viewShowing = null;
-          return false;
-        }
-      }
-
       // Now we have to transition the panel. If we've got an older transition
       // still running, make sure to clean it up.
       await this._cleanupTransitionPhase();
       if (!showingSameView && this._panel.state == "open") {
         await this._transitionViews(previousViewNode, viewNode, reverse, anchor);
         nextPanelView.focusSelectedElement();
       } else {
         this.hideAllViewsExcept(nextPanelView);
@@ -992,17 +985,16 @@ this.PanelMultiView = class extends this
       case "popupshown":
         // Now that the main view is visible, we can check the height of the
         // description elements it contains.
         PanelView.forNode(this._mainView).descriptionHeightWorkaround();
         break;
       case "popuphidden": {
         // WebExtensions consumers can hide the popup from viewshowing, or
         // mid-transition, which disrupts our state:
-        this._viewShowing = null;
         this._transitioning = false;
         this.node.removeAttribute("panelopen");
         // Raise the ViewHiding event for the current view.
         this._cleanupTransitionPhase();
         this.hideAllViewsExcept(null);
         this.window.removeEventListener("keydown", this);
         this._panel.removeEventListener("mousemove", this);
         this.openViews.forEach(panelView => panelView.clearNavigation());

--- a/browser/components/places/content/browserPlacesViews.js
+++ b/browser/components/places/content/browserPlacesViews.js
@@ -2250,20 +2250,16 @@ this.PlacesPanelview = class extends Pla
     } else {
       panelview.removeAttribute("emptyplacesresult");
       try {
         panelview.removeChild(panelview._emptyMenuitem);
       } catch (ex) {}
     }
   }
 
-  _isPopupOpen() {
-    return this.panel.state == "open" && this.panelMultiView.current == this._viewElt;
-  }
-
   _onPopupHidden(event) {
     let panelview = event.originalTarget;
     let placesNode = panelview._placesNode;
     // Avoid handling ViewHiding of inner views
     if (placesNode && PlacesUIUtils.getViewForNode(panelview) == this) {
       // UI performance: folder queries are cheap, keep the resultnode open
       // so we don't rebuild its contents whenever the popup is reopened.
       // Though, we want to always close feed containers so their expiration