diff --git a/.eslintrc.js b/.eslintrc.js
index 4959b133a0..9ae51f9bc5 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -30,6 +30,24 @@ module.exports = {
 
             "quotes": "off",
             "no-extra-boolean-cast": "off",
+            "no-restricted-properties": [
+                "error",
+                ...buildRestrictedPropertiesOptions(
+                    ["window.innerHeight", "window.innerWidth", "window.visualViewport"],
+                    "Use UIStore to access window dimensions instead",
+                ),
+            ],
         },
     }],
 };
+
+function buildRestrictedPropertiesOptions(properties, message) {
+    return properties.map(prop => {
+        const [object, property] = prop.split(".");
+        return {
+            object,
+            property,
+            message,
+        };
+    });
+}
diff --git a/src/components/structures/ContextMenu.tsx b/src/components/structures/ContextMenu.tsx
index ad0f75e162..9d8665c176 100644
--- a/src/components/structures/ContextMenu.tsx
+++ b/src/components/structures/ContextMenu.tsx
@@ -23,6 +23,7 @@ import classNames from "classnames";
 import {Key} from "../../Keyboard";
 import {Writeable} from "../../@types/common";
 import {replaceableComponent} from "../../utils/replaceableComponent";
+import UIStore from "../../stores/UIStore";
 
 // Shamelessly ripped off Modal.js.  There's probably a better way
 // of doing reusable widgets like dialog boxes & menus where we go and
@@ -410,12 +411,12 @@ export const aboveLeftOf = (elementRect: DOMRect, chevronFace = ChevronFace.None
     const buttonBottom = elementRect.bottom + window.pageYOffset;
     const buttonTop = elementRect.top + window.pageYOffset;
     // Align the right edge of the menu to the right edge of the button
-    menuOptions.right = window.innerWidth - buttonRight;
+    menuOptions.right = UIStore.instance.windowWidth - buttonRight;
     // Align the menu vertically on whichever side of the button has more space available.
-    if (buttonBottom < window.innerHeight / 2) {
+    if (buttonBottom < UIStore.instance.windowHeight / 2) {
         menuOptions.top = buttonBottom + vPadding;
     } else {
-        menuOptions.bottom = (window.innerHeight - buttonTop) + vPadding;
+        menuOptions.bottom = (UIStore.instance.windowHeight - buttonTop) + vPadding;
     }
 
     return menuOptions;
@@ -430,12 +431,12 @@ export const alwaysAboveLeftOf = (elementRect: DOMRect, chevronFace = ChevronFac
     const buttonBottom = elementRect.bottom + window.pageYOffset;
     const buttonTop = elementRect.top + window.pageYOffset;
     // Align the right edge of the menu to the right edge of the button
-    menuOptions.right = window.innerWidth - buttonRight;
+    menuOptions.right = UIStore.instance.windowWidth - buttonRight;
     // Align the menu vertically on whichever side of the button has more space available.
-    if (buttonBottom < window.innerHeight / 2) {
+    if (buttonBottom < UIStore.instance.windowHeight / 2) {
         menuOptions.top = buttonBottom + vPadding;
     } else {
-        menuOptions.bottom = (window.innerHeight - buttonTop) + vPadding;
+        menuOptions.bottom = (UIStore.instance.windowHeight - buttonTop) + vPadding;
     }
 
     return menuOptions;
@@ -451,7 +452,7 @@ export const alwaysAboveRightOf = (elementRect: DOMRect, chevronFace = ChevronFa
     // Align the left edge of the menu to the left edge of the button
     menuOptions.left = buttonLeft;
     // Align the menu vertically above the menu
-    menuOptions.bottom = (window.innerHeight - buttonTop) + vPadding;
+    menuOptions.bottom = (UIStore.instance.windowHeight - buttonTop) + vPadding;
 
     return menuOptions;
 };
diff --git a/src/components/structures/LeftPanel.tsx b/src/components/structures/LeftPanel.tsx
index 465d4cac49..e929306940 100644
--- a/src/components/structures/LeftPanel.tsx
+++ b/src/components/structures/LeftPanel.tsx
@@ -43,6 +43,7 @@ import {replaceableComponent} from "../../utils/replaceableComponent";
 import {mediaFromMxc} from "../../customisations/Media";
 import SpaceStore, {UPDATE_SELECTED_SPACE} from "../../stores/SpaceStore";
 import { getKeyBindingsManager, RoomListAction } from "../../KeyBindingsManager";
+import UIStore from "../../stores/UIStore";
 
 interface IProps {
     isMinimized: boolean;
@@ -223,7 +224,8 @@ export default class LeftPanel extends React.Component<IProps, IState> {
                     header.classList.add("mx_RoomSublist_headerContainer_stickyBottom");
                 }
 
-                const offset = window.innerHeight - (list.parentElement.offsetTop + list.parentElement.offsetHeight);
+                const offset = UIStore.instance.windowHeight -
+                    (list.parentElement.offsetTop + list.parentElement.offsetHeight);
                 const newBottom = `${offset}px`;
                 if (header.style.bottom !== newBottom) {
                     header.style.bottom = newBottom;
diff --git a/src/components/structures/LeftPanelWidget.tsx b/src/components/structures/LeftPanelWidget.tsx
index 89c0744cf8..16142069c4 100644
--- a/src/components/structures/LeftPanelWidget.tsx
+++ b/src/components/structures/LeftPanelWidget.tsx
@@ -27,6 +27,7 @@ import WidgetUtils, {IWidgetEvent} from "../../utils/WidgetUtils";
 import {useAccountData} from "../../hooks/useAccountData";
 import AppTile from "../views/elements/AppTile";
 import {useSettingValue} from "../../hooks/useSettings";
+import UIStore from "../../stores/UIStore";
 
 const MIN_HEIGHT = 100;
 const MAX_HEIGHT = 500; // or 50% of the window height
@@ -63,7 +64,7 @@ const LeftPanelWidget: React.FC = () => {
         content = <Resizable
             size={{height} as any}
             minHeight={MIN_HEIGHT}
-            maxHeight={Math.min(window.innerHeight / 2, MAX_HEIGHT)}
+            maxHeight={Math.min(UIStore.instance.windowHeight / 2, MAX_HEIGHT)}
             onResizeStop={(e, dir, ref, d) => {
                 setHeight(height + d.height);
             }}
diff --git a/src/components/structures/MatrixChat.tsx b/src/components/structures/MatrixChat.tsx
index 1d794b05c4..c01437b313 100644
--- a/src/components/structures/MatrixChat.tsx
+++ b/src/components/structures/MatrixChat.tsx
@@ -1819,7 +1819,7 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
 
     handleResize = () => {
         const LHS_THRESHOLD = 1000;
-        const width = UIStore.instance.windowWith;
+        const width = UIStore.instance.windowWidth;
 
         if (width <= LHS_THRESHOLD && !this.state.collapseLhs) {
             dis.dispatch({ action: 'hide_left_panel' });
diff --git a/src/components/structures/RoomView.tsx b/src/components/structures/RoomView.tsx
index d822b6a839..e3b0c10fb2 100644
--- a/src/components/structures/RoomView.tsx
+++ b/src/components/structures/RoomView.tsx
@@ -83,6 +83,7 @@ import { objectHasDiff } from "../../utils/objects";
 import SpaceRoomView from "./SpaceRoomView";
 import { IOpts } from "../../createRoom";
 import {replaceableComponent} from "../../utils/replaceableComponent";
+import UIStore from "../../stores/UIStore";
 
 const DEBUG = false;
 let debuglog = function(msg: string) {};
@@ -1585,7 +1586,7 @@ export default class RoomView extends React.Component<IProps, IState> {
         // a maxHeight on the underlying remote video tag.
 
         // header + footer + status + give us at least 120px of scrollback at all times.
-        let auxPanelMaxHeight = window.innerHeight -
+        let auxPanelMaxHeight = UIStore.instance.windowHeight -
                 (54 + // height of RoomHeader
                  36 + // height of the status area
                  51 + // minimum height of the message compmoser
diff --git a/src/components/views/directory/NetworkDropdown.tsx b/src/components/views/directory/NetworkDropdown.tsx
index 66b7321ce0..08787812f6 100644
--- a/src/components/views/directory/NetworkDropdown.tsx
+++ b/src/components/views/directory/NetworkDropdown.tsx
@@ -38,13 +38,14 @@ import withValidation from "../elements/Validation";
 import { SettingLevel } from "../../../settings/SettingLevel";
 import TextInputDialog from "../dialogs/TextInputDialog";
 import QuestionDialog from "../dialogs/QuestionDialog";
+import UIStore from "../../../stores/UIStore";
 
 export const ALL_ROOMS = Symbol("ALL_ROOMS");
 
 const SETTING_NAME = "room_directory_servers";
 
 const inPlaceOf = (elementRect: Pick<DOMRect, "right" | "top">) => ({
-    right: window.innerWidth - elementRect.right,
+    right: UIStore.instance.windowWidth - elementRect.right,
     top: elementRect.top,
     chevronOffset: 0,
     chevronFace: ChevronFace.None,
diff --git a/src/components/views/elements/Tooltip.tsx b/src/components/views/elements/Tooltip.tsx
index 062d26c852..7e9ce9745c 100644
--- a/src/components/views/elements/Tooltip.tsx
+++ b/src/components/views/elements/Tooltip.tsx
@@ -22,6 +22,7 @@ import React, {Component, CSSProperties} from 'react';
 import ReactDOM from 'react-dom';
 import classNames from 'classnames';
 import {replaceableComponent} from "../../../utils/replaceableComponent";
+import UIStore from "../../../stores/UIStore";
 
 const MIN_TOOLTIP_HEIGHT = 25;
 
@@ -97,15 +98,15 @@ export default class Tooltip extends React.Component<IProps> {
             // we need so that we're still centered.
             offset = Math.floor(parentBox.height - MIN_TOOLTIP_HEIGHT);
         }
-
+        const width = UIStore.instance.windowWidth;
         const baseTop = (parentBox.top - 2 + this.props.yOffset) + window.pageYOffset;
         const top = baseTop + offset;
-        const right = window.innerWidth - parentBox.right - window.pageXOffset - 16;
+        const right = width - parentBox.right - window.pageXOffset - 16;
         const left = parentBox.right + window.pageXOffset + 6;
         const horizontalCenter = parentBox.right - window.pageXOffset - (parentBox.width / 2);
         switch (this.props.alignment) {
             case Alignment.Natural:
-                if (parentBox.right > window.innerWidth / 2) {
+                if (parentBox.right > width / 2) {
                     style.right = right;
                     style.top = top;
                     break;
diff --git a/src/components/views/messages/TextualBody.js b/src/components/views/messages/TextualBody.js
index b963e741a1..dc644f1009 100644
--- a/src/components/views/messages/TextualBody.js
+++ b/src/components/views/messages/TextualBody.js
@@ -36,6 +36,7 @@ import {toRightOf} from "../../structures/ContextMenu";
 import {copyPlaintext} from "../../../utils/strings";
 import AccessibleTooltipButton from "../elements/AccessibleTooltipButton";
 import {replaceableComponent} from "../../../utils/replaceableComponent";
+import UIStore from "../../../stores/UIStore";
 
 @replaceableComponent("views.messages.TextualBody")
 export default class TextualBody extends React.Component {
@@ -143,7 +144,7 @@ export default class TextualBody extends React.Component {
     _addCodeExpansionButton(div, pre) {
         // Calculate how many percent does the pre element take up.
         // If it's less than 30% we don't add the expansion button.
-        const percentageOfViewport = pre.offsetHeight / window.innerHeight * 100;
+        const percentageOfViewport = pre.offsetHeight / UIStore.instance.windowHeight * 100;
         if (percentageOfViewport < 30) return;
 
         const button = document.createElement("span");
diff --git a/src/components/views/right_panel/RoomSummaryCard.tsx b/src/components/views/right_panel/RoomSummaryCard.tsx
index 88928290f4..937037f644 100644
--- a/src/components/views/right_panel/RoomSummaryCard.tsx
+++ b/src/components/views/right_panel/RoomSummaryCard.tsx
@@ -46,6 +46,7 @@ import WidgetContextMenu from "../context_menus/WidgetContextMenu";
 import {useRoomMemberCount} from "../../../hooks/useRoomMembers";
 import { Container, MAX_PINNED, WidgetLayoutStore } from "../../../stores/widgets/WidgetLayoutStore";
 import RoomName from "../elements/RoomName";
+import UIStore from "../../../stores/UIStore";
 
 interface IProps {
     room: Room;
@@ -116,8 +117,8 @@ const AppRow: React.FC<IAppRowProps> = ({ app, room }) => {
         const rect = handle.current.getBoundingClientRect();
         contextMenu = <WidgetContextMenu
             chevronFace={ChevronFace.None}
-            right={window.innerWidth - rect.right}
-            bottom={window.innerHeight - rect.top}
+            right={UIStore.instance.windowWidth - rect.right}
+            bottom={UIStore.instance.windowHeight - rect.top}
             onFinished={closeMenu}
             app={app}
         />;
diff --git a/src/components/views/right_panel/UserInfo.tsx b/src/components/views/right_panel/UserInfo.tsx
index 9798b282f6..6e56b9259b 100644
--- a/src/components/views/right_panel/UserInfo.tsx
+++ b/src/components/views/right_panel/UserInfo.tsx
@@ -66,6 +66,7 @@ import { SetRightPanelPhasePayload } from "../../../dispatcher/payloads/SetRight
 import RoomAvatar from "../avatars/RoomAvatar";
 import RoomName from "../elements/RoomName";
 import {mediaFromMxc} from "../../../customisations/Media";
+import UIStore from "../../../stores/UIStore";
 
 export interface IDevice {
     deviceId: string;
@@ -1448,8 +1449,8 @@ const UserInfoHeader: React.FC<{
                     <MemberAvatar
                         key={member.userId} // to instantly blank the avatar when UserInfo changes members
                         member={member}
-                        width={2 * 0.3 * window.innerHeight} // 2x@30vh
-                        height={2 * 0.3 * window.innerHeight} // 2x@30vh
+                        width={2 * 0.3 * UIStore.instance.windowHeight} // 2x@30vh
+                        height={2 * 0.3 * UIStore.instance.windowHeight} // 2x@30vh
                         resizeMethod="scale"
                         fallbackUserId={member.userId}
                         onClick={onMemberAvatarClick}
diff --git a/src/components/views/right_panel/WidgetCard.tsx b/src/components/views/right_panel/WidgetCard.tsx
index 56e522e206..d7493e0512 100644
--- a/src/components/views/right_panel/WidgetCard.tsx
+++ b/src/components/views/right_panel/WidgetCard.tsx
@@ -30,6 +30,7 @@ import { Action } from "../../../dispatcher/actions";
 import { ChevronFace, ContextMenuButton, useContextMenu } from "../../structures/ContextMenu";
 import WidgetContextMenu from "../context_menus/WidgetContextMenu";
 import { Container, WidgetLayoutStore } from "../../../stores/widgets/WidgetLayoutStore";
+import UIStore from "../../../stores/UIStore";
 
 interface IProps {
     room: Room;
@@ -65,7 +66,7 @@ const WidgetCard: React.FC<IProps> = ({ room, widgetId, onClose }) => {
         contextMenu = (
             <WidgetContextMenu
                 chevronFace={ChevronFace.None}
-                right={window.innerWidth - rect.right - 12}
+                right={UIStore.instance.windowWidth - rect.right - 12}
                 top={rect.bottom + 12}
                 onFinished={closeMenu}
                 app={app}
diff --git a/src/components/views/rooms/AppsDrawer.js b/src/components/views/rooms/AppsDrawer.js
index 3ef8d71682..693ec8bc80 100644
--- a/src/components/views/rooms/AppsDrawer.js
+++ b/src/components/views/rooms/AppsDrawer.js
@@ -36,6 +36,7 @@ import {Container, WidgetLayoutStore} from "../../../stores/widgets/WidgetLayout
 import {clamp, percentageOf, percentageWithin} from "../../../utils/numbers";
 import {useStateCallback} from "../../../hooks/useStateCallback";
 import {replaceableComponent} from "../../../utils/replaceableComponent";
+import UIStore from "../../../stores/UIStore";
 
 @replaceableComponent("views.rooms.AppsDrawer")
 export default class AppsDrawer extends React.Component {
@@ -290,7 +291,7 @@ const PersistentVResizer = ({
 
     // Arbitrary defaults to avoid NaN problems. 100 px or 3/4 of the visible window.
     if (!minHeight) minHeight = 100;
-    if (!maxHeight) maxHeight = (window.innerHeight / 4) * 3;
+    if (!maxHeight) maxHeight = (UIStore.instance.windowHeight / 4) * 3;
 
     // Convert from percentage to height. Note that the default height is 280px.
     if (defaultHeight) {
diff --git a/src/stores/UIStore.ts b/src/stores/UIStore.ts
index 62b73a14f6..8e3a6fb31a 100644
--- a/src/stores/UIStore.ts
+++ b/src/stores/UIStore.ts
@@ -15,6 +15,8 @@ limitations under the License.
 */
 
 import EventEmitter from "events";
+import ResizeObserver from 'resize-observer-polyfill';
+import ResizeObserverEntry from 'resize-observer-polyfill/src/ResizeObserverEntry';
 
 export enum UI_EVENTS {
     Resize = "resize"
@@ -28,13 +30,15 @@ export default class UIStore extends EventEmitter {
 
     private resizeObserver: ResizeObserver;
 
-    public windowWith: number;
+    public windowWidth: number;
     public windowHeight: number;
 
     constructor() {
         super();
 
-        this.windowWith = window.innerWidth;
+        // eslint-disable-next-line no-restricted-properties
+        this.windowWidth = window.innerWidth;
+        // eslint-disable-next-line no-restricted-properties
         this.windowHeight = window.innerHeight;
 
         this.resizeObserver = new ResizeObserver(this.resizeObserverCallback);
@@ -61,7 +65,7 @@ export default class UIStore extends EventEmitter {
             .find(entry => entry.target === document.body)
             .contentRect;
 
-        this.windowWith = width;
+        this.windowWidth = width;
         this.windowHeight = height;
 
         this.emit(UI_EVENTS.Resize, entries);