Fixed: Rotating mobile device when modal is open won't reset modal

Co-Authored-By: Mark McDowall <markus101@users.noreply.github.com>

frontend/src/Components/Page/PageContentBody.js

@@ -1,5 +1,6 @@
 import PropTypes from 'prop-types';
 import React, { Component } from 'react';
+import { isMobile as isMobileUtil } from 'Utilities/mobile';
 import { isLocked } from 'Utilities/scrollLock';
 import { scrollDirections } from 'Helpers/Props';
 import OverlayScroller from 'Components/Scroller/OverlayScroller';
@@ -8,6 +9,15 @@ import styles from './PageContentBody.css';
 
 class PageContentBody extends Component {
 
+  //
+  // Lifecycle
+
+  constructor(props, context) {
+    super(props, context);
+
+    this._isMobile = isMobileUtil();
+  }
+
   //
   // Listeners
 
@@ -26,13 +36,12 @@ class PageContentBody extends Component {
     const {
       className,
       innerClassName,
-      isSmallScreen,
       children,
       dispatch,
       ...otherProps
     } = this.props;
 
-    const ScrollerComponent = isSmallScreen ? Scroller : OverlayScroller;
+    const ScrollerComponent = this._isMobile ? Scroller : OverlayScroller;
 
     return (
       <ScrollerComponent
@@ -52,7 +61,6 @@ class PageContentBody extends Component {
 PageContentBody.propTypes = {
   className: PropTypes.string,
   innerClassName: PropTypes.string,
-  isSmallScreen: PropTypes.bool.isRequired,
   children: PropTypes.node.isRequired,
   onScroll: PropTypes.func,
   dispatch: PropTypes.func