diff --git a/dev/Knoin/Knoin.js b/dev/Knoin/Knoin.js
index a4cd56a40..80168fb06 100644
--- a/dev/Knoin/Knoin.js
+++ b/dev/Knoin/Knoin.js
@@ -4,8 +4,7 @@ import { doc, $htmlCL } from 'Common/Globals';
 import { isNonEmptyArray } from 'Common/Utils';
 
 let currentScreen = null,
-	defaultScreenName = '',
-	popupVisibilityNames = [];
+	defaultScreenName = '';
 
 const SCREENS = {},
 	autofocus = dom => {
@@ -13,7 +12,7 @@ const SCREENS = {},
 		af && af.focus();
 	};
 
-export const popupVisibility = ko.computed(() => 0 < popupVisibilityNames.length);
+export const popupVisibilityNames = ko.observableArray([]);
 
 export const ViewType = {
 	Popup: 'Popups',
@@ -109,7 +108,7 @@ function buildViewModel(ViewModelClass, vmScreen) {
 
 				vm.modalVisibility.subscribe(value => {
 					if (value) {
-						vmDom.style.zIndex = 3000 + popupVisibilityNames.length + 10;
+						vmDom.style.zIndex = 3000 + popupVisibilityNames().length + 10;
 						vmDom.hidden = false;
 						vm.storeAndSetScope();
 						popupVisibilityNames.push(vm.viewModelName);
@@ -121,7 +120,7 @@ function buildViewModel(ViewModelClass, vmScreen) {
 						vm.onHide && vm.onHide();
 						vmDom.classList.remove('show');
 						vm.restoreScope();
-						popupVisibilityNames = popupVisibilityNames.filter(v=>v!==vm.viewModelName);
+						popupVisibilityNames(popupVisibilityNames.filter(v=>v!==vm.viewModelName));
 					}
 					vmDom.setAttribute('aria-hidden', !value);
 				});
diff --git a/dev/View/User/MailBox/MessageList.js b/dev/View/User/MailBox/MessageList.js
index df688cee5..87acdc9b9 100644
--- a/dev/View/User/MailBox/MessageList.js
+++ b/dev/View/User/MailBox/MessageList.js
@@ -39,7 +39,7 @@ import { ThemeStore } from 'Stores/Theme';
 
 import Remote from 'Remote/User/Fetch';
 
-import { decorateKoCommands, showScreenPopup, popupVisibility } from 'Knoin/Knoin';
+import { decorateKoCommands, showScreenPopup, popupVisibilityNames } from 'Knoin/Knoin';
 import { AbstractViewRight } from 'Knoin/AbstractViews';
 
 import { FolderClearPopupView } from 'View/Popup/FolderClear';
@@ -67,7 +67,7 @@ export class MessageListMailBoxUserView extends AbstractViewRight {
 		this.allowMessageListActions = Settings.capa(Capa.MessageListActions);
 		this.allowDangerousActions = Settings.capa(Capa.DangerousActions);
 
-		this.popupVisibility = popupVisibility;
+		this.popupVisibility = ko.computed(() => 0 < popupVisibilityNames().length);
 
 		this.message = MessageUserStore.message;
 		this.messageList = MessageUserStore.list;