SEBWIN-312: Implemented thumbnails of open windows for desktop taskview.

SafeExamBrowser.Applications.Contracts/IApplicationWindow.cs

@@ -6,6 +6,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
+using System;
 using SafeExamBrowser.Applications.Contracts.Events;
 using SafeExamBrowser.Applications.Contracts.Resources.Icons;
 
@@ -16,6 +17,11 @@ namespace SafeExamBrowser.Applications.Contracts
 	/// </summary>
 	public interface IApplicationWindow
 	{
+		/// <summary>
+		/// The native handle of the window.
+		/// </summary>
+		IntPtr Handle { get; }
+
 		/// <summary>
 		/// The icon of the window.
 		/// </summary>

SafeExamBrowser.Applications/ExternalApplicationWindow.cs

@@ -18,7 +18,7 @@ namespace SafeExamBrowser.Applications
 	{
 		private INativeMethods nativeMethods;
 
-		internal IntPtr Handle { get; }
+		public IntPtr Handle { get; }
 		public IconResource Icon { get; private set; }
 		public string Title { get; private set; }
 

SafeExamBrowser.Browser/BrowserApplicationInstance.cs

@@ -51,6 +51,7 @@ namespace SafeExamBrowser.Browser
 
 		internal int Id { get; }
 
+		public IntPtr Handle { get; private set; }
 		public IconResource Icon { get; private set; }
 		public string Title { get; private set; }
 
@@ -178,6 +179,8 @@ namespace SafeExamBrowser.Browser
 			window.UpdateZoomLevel(CalculateZoomPercentage());
 			window.Show();
 
+			Handle = window.Handle;
+
 			logger.Debug("Initialized browser window.");
 		}
 

SafeExamBrowser.Client/CompositionRoot.cs

@@ -71,7 +71,7 @@ namespace SafeExamBrowser.Client
 		private IRuntimeProxy runtimeProxy;
 		private ISystemInfo systemInfo;
 		private ITaskbar taskbar;
-		private ITaskView taskView;
+		private ITaskView taskview;
 		private IText text;
 		private ITextResource textResource;
 		private IUserInterfaceFactory uiFactory;
@@ -95,7 +95,7 @@ namespace SafeExamBrowser.Client
 			uiFactory = BuildUserInterfaceFactory();
 			runtimeProxy = new RuntimeProxy(runtimeHostUri, new ProxyObjectFactory(), ModuleLogger(nameof(RuntimeProxy)), Interlocutor.Client);
 			taskbar = BuildTaskbar();
-			taskView = BuildTaskView();
+			taskview = BuildTaskView();
 
 			var processFactory = new ProcessFactory(ModuleLogger(nameof(ProcessFactory)));
 			var applicationMonitor = new ApplicationMonitor(TWO_SECONDS, ModuleLogger(nameof(ApplicationMonitor)), nativeMethods, processFactory);
@@ -199,7 +199,7 @@ namespace SafeExamBrowser.Client
 		{
 			var moduleLogger = ModuleLogger(nameof(BrowserApplication));
 			var browser = new BrowserApplication(context.AppConfig, context.Settings.Browser, messageBox, moduleLogger, text, uiFactory);
-			var operation = new BrowserOperation(actionCenter, context, logger, taskbar, taskView, uiFactory);
+			var operation = new BrowserOperation(actionCenter, context, logger, taskbar, taskview, uiFactory);
 
 			context.Browser = browser;
 
@@ -258,7 +258,7 @@ namespace SafeExamBrowser.Client
 				powerSupply,
 				systemInfo,
 				taskbar,
-				taskView,
+				taskview,
 				text,
 				uiFactory,
 				wirelessAdapter);
@@ -311,7 +311,7 @@ namespace SafeExamBrowser.Client
 				case UserInterfaceMode.Mobile:
 					return new Mobile.TaskView();
 				default:
-					return new Desktop.TaskView();
+					return new Desktop.Taskview();
 			}
 		}
 

SafeExamBrowser.Client/Operations/BrowserOperation.cs

@@ -20,7 +20,7 @@ namespace SafeExamBrowser.Client.Operations
 		private IActionCenter actionCenter;
 		private ILogger logger;
 		private ITaskbar taskbar;
-		private ITaskView taskView;
+		private ITaskView taskview;
 		private IUserInterfaceFactory uiFactory;
 
 		public override event ActionRequiredEventHandler ActionRequired { add { } remove { } }
@@ -31,13 +31,13 @@ namespace SafeExamBrowser.Client.Operations
 			ClientContext context,
 			ILogger logger,
 			ITaskbar taskbar,
-			ITaskView taskView,
+			ITaskView taskview,
 			IUserInterfaceFactory uiFactory) : base(context)
 		{
 			this.actionCenter = actionCenter;
 			this.logger = logger;
 			this.taskbar = taskbar;
-			this.taskView = taskView;
+			this.taskview = taskview;
 			this.uiFactory = uiFactory;
 		}
 
@@ -58,7 +58,7 @@ namespace SafeExamBrowser.Client.Operations
 				taskbar.AddApplicationControl(uiFactory.CreateApplicationControl(Context.Browser, Location.Taskbar), true);
 			}
 
-			taskView.Add(Context.Browser);
+			taskview.Add(Context.Browser);
 
 			return OperationResult.Success;
 		}

SafeExamBrowser.Client/Operations/ShellOperation.cs

@@ -35,7 +35,7 @@ namespace SafeExamBrowser.Client.Operations
 		private IPowerSupply powerSupply;
 		private ISystemInfo systemInfo;
 		private ITaskbar taskbar;
-		private ITaskView taskView;
+		private ITaskView taskview;
 		private IText text;
 		private IUserInterfaceFactory uiFactory;
 		private IWirelessAdapter wirelessAdapter;
@@ -56,7 +56,7 @@ namespace SafeExamBrowser.Client.Operations
 			IPowerSupply powerSupply,
 			ISystemInfo systemInfo,
 			ITaskbar taskbar,
-			ITaskView taskView,
+			ITaskView taskview,
 			IText text,
 			IUserInterfaceFactory uiFactory,
 			IWirelessAdapter wirelessAdapter) : base(context)
@@ -73,7 +73,7 @@ namespace SafeExamBrowser.Client.Operations
 			this.systemInfo = systemInfo;
 			this.text = text;
 			this.taskbar = taskbar;
-			this.taskView = taskView;
+			this.taskview = taskview;
 			this.uiFactory = uiFactory;
 			this.wirelessAdapter = wirelessAdapter;
 		}
@@ -116,7 +116,7 @@ namespace SafeExamBrowser.Client.Operations
 
 				if (Context.Settings.Keyboard.AllowAltTab && activator is ITaskViewActivator taskViewActivator)
 				{
-					taskView.Register(taskViewActivator);
+					taskview.Register(taskViewActivator);
 					taskViewActivator.Start();
 				}
 
@@ -177,7 +177,7 @@ namespace SafeExamBrowser.Client.Operations
 
 			foreach (var application in Context.Applications)
 			{
-				taskView.Add(application);
+				taskview.Add(application);
 			}
 		}
 

SafeExamBrowser.UserInterface.Contracts/Browser/IBrowserWindow.cs

@@ -6,6 +6,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
+using System;
 using SafeExamBrowser.Applications.Contracts.Resources.Icons;
 using SafeExamBrowser.UserInterface.Contracts.Browser.Events;
 using SafeExamBrowser.UserInterface.Contracts.Windows;
@@ -26,6 +27,11 @@ namespace SafeExamBrowser.UserInterface.Contracts.Browser
 		/// Enables the forward navigation button.
 		/// </summary>
 		bool CanNavigateForwards { set; }
+		
+		/// <summary>
+		/// The native handle of the window.
+		/// </summary>
+		IntPtr Handle { get; }
 
 		/// <summary>
 		/// Event fired when the user changed the URL.

SafeExamBrowser.UserInterface.Desktop/BrowserWindow.xaml.cs

@@ -12,6 +12,7 @@ using System.Threading.Tasks;
 using System.Windows;
 using System.Windows.Controls.Primitives;
 using System.Windows.Input;
+using System.Windows.Interop;
 using System.Windows.Media;
 using System.Windows.Media.Imaging;
 using SafeExamBrowser.Applications.Contracts.Resources.Icons;
@@ -40,6 +41,7 @@ namespace SafeExamBrowser.UserInterface.Desktop
 
 		public bool CanNavigateBackwards { set => Dispatcher.Invoke(() => BackwardButton.IsEnabled = value); }
 		public bool CanNavigateForwards { set => Dispatcher.Invoke(() => ForwardButton.IsEnabled = value); }
+		public IntPtr Handle { get; private set; }
 
 		public event AddressChangedEventHandler AddressChanged;
 		public event ActionRequestedEventHandler BackwardNavigationRequested;
@@ -157,6 +159,8 @@ namespace SafeExamBrowser.UserInterface.Desktop
 
 		private void BrowserWindow_Loaded(object sender, RoutedEventArgs e)
 		{
+			Handle = new WindowInteropHelper(this).Handle;
+
 			if (isMainWindow)
 			{
 				WindowUtility.DisableCloseButtonFor(this);

SafeExamBrowser.UserInterface.Desktop/Controls/TaskViewWindowControl.xaml

@@ -1,4 +1,4 @@
-<UserControl x:Class="SafeExamBrowser.UserInterface.Desktop.Controls.TaskViewWindowControl"
+<UserControl x:Class="SafeExamBrowser.UserInterface.Desktop.Controls.TaskviewWindowControl"
              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
@@ -11,11 +11,20 @@
             </ResourceDictionary.MergedDictionaries>
         </ResourceDictionary>
     </UserControl.Resources>
-    <Grid Margin="5" Height="150" Width="250">
+    <Grid Margin="5" Height="175" Width="250">
         <Border Name="Indicator" Background="{StaticResource BackgroundTransparentEmphasisBrush}" BorderThickness="0" Visibility="Hidden" />
-        <StackPanel HorizontalAlignment="Center" Orientation="Vertical" VerticalAlignment="Center">
+        <Grid Margin="5">
-            <ContentControl Name="Icon" MaxWidth="40" />
+            <Grid.ColumnDefinitions>
-            <TextBlock Name="Title" Margin="10" Foreground="{StaticResource PrimaryTextBrush}" TextTrimming="CharacterEllipsis" />
+                <ColumnDefinition Width="Auto" />
-        </StackPanel>
+                <ColumnDefinition Width="*" />
+            </Grid.ColumnDefinitions>
+            <Grid.RowDefinitions>
+                <RowDefinition Height="Auto" />
+                <RowDefinition Height="*" />
+            </Grid.RowDefinitions>
+            <ContentControl Grid.Row="0" Grid.Column="0" Name="Icon" Margin="0,0,5,0" Height="16" />
+            <TextBlock Grid.Row="0" Grid.Column="1" Name="Title" Foreground="{StaticResource PrimaryTextBrush}" VerticalAlignment="Center" TextTrimming="CharacterEllipsis" />
+            <ContentControl Grid.Row="1" Grid.ColumnSpan="2" Name="Placeholder" Margin="0,5,0,0" />
+        </Grid>
     </Grid>
 </UserControl>

SafeExamBrowser.UserInterface.Desktop/Controls/TaskViewWindowControl.xaml.cs

@@ -6,21 +6,26 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
+using System;
 using System.Windows;
 using System.Windows.Controls;
+using System.Windows.Threading;
 using SafeExamBrowser.Applications.Contracts;
 using SafeExamBrowser.Applications.Contracts.Resources.Icons;
 using SafeExamBrowser.UserInterface.Shared.Utilities;
 
 namespace SafeExamBrowser.UserInterface.Desktop.Controls
 {
-	public partial class TaskViewWindowControl : UserControl
+	public partial class TaskviewWindowControl : UserControl
 	{
+		private Taskview taskview;
+		private IntPtr thumbnail;
 		private IApplicationWindow window;
 
-		public TaskViewWindowControl(IApplicationWindow window)
+		public TaskviewWindowControl(IApplicationWindow window, Taskview taskview)
 		{
 			this.window = window;
+			this.taskview = taskview;
 
 			InitializeComponent();
 			InitializeControl();
@@ -33,35 +38,128 @@ namespace SafeExamBrowser.UserInterface.Desktop.Controls
 
 		internal void Deselect()
 		{
-			Icon.MaxWidth = 40;
 			Indicator.Visibility = Visibility.Hidden;
 			Title.FontWeight = FontWeights.Normal;
 		}
 
+		internal void Destroy()
+		{
+			if (thumbnail != IntPtr.Zero)
+			{
+				Thumbnail.DwmUnregisterThumbnail(thumbnail);
+			}
+		}
+
 		internal void Select()
 		{
-			Icon.MaxWidth = 50;
 			Indicator.Visibility = Visibility.Visible;
 			Title.FontWeight = FontWeights.SemiBold;
 		}
 
+		internal void Update()
+		{
+			if (!IsLoaded || !IsVisible)
+			{
+				return;
+			}
+
+			if (thumbnail == IntPtr.Zero && taskview.Handle != IntPtr.Zero && window.Handle != IntPtr.Zero)
+			{
+				Thumbnail.DwmRegisterThumbnail(taskview.Handle, window.Handle, out thumbnail);
+			}
+
+			if (thumbnail != IntPtr.Zero)
+			{
+				Thumbnail.DwmQueryThumbnailSourceSize(thumbnail, out var size);
+
+				var destination = CalculatePhysicalDestination(size);
+				var properties = new Thumbnail.Properties
+				{
+					Destination = destination,
+					Flags = Thumbnail.DWM_TNP_RECTDESTINATION | Thumbnail.DWM_TNP_VISIBLE,
+					Visible = true
+				};
+
+				Thumbnail.DwmUpdateThumbnailProperties(thumbnail, ref properties);
+			}
+		}
+
+		private void TaskViewWindowControl_IsVisibleChanged(object sender, DependencyPropertyChangedEventArgs e)
+		{
+			if (e.NewValue as bool? == true)
+			{
+				Update();
+			}
+		}
+
+		private void Window_TitleChanged(string title)
+		{
+			Dispatcher.InvokeAsync(() => Title.Text = title);
+		}
+
+		private void Window_IconChanged(IconResource icon)
+		{
+			Dispatcher.InvokeAsync(() => Icon.Content = IconResourceLoader.Load(window.Icon));
+		}
+
+		private Thumbnail.Rectangle CalculatePhysicalDestination(Thumbnail.Size size)
+		{
+			var controlToTaskview = TransformToVisual(taskview);
+			var placeholderToControl = Placeholder.TransformToVisual(this);
+			var placeholderLeft = placeholderToControl.Transform(new Point(0, 0)).X;
+			var placeholderTop = placeholderToControl.Transform(new Point(0, 0)).Y;
+			var placeholderRight = placeholderToControl.Transform(new Point(Placeholder.ActualWidth, 0)).X;
+			var placeholderBottom = placeholderToControl.Transform(new Point(0, Placeholder.ActualHeight)).Y;
+
+			var physicalBounds = new Thumbnail.Rectangle
+			{
+				Left = (int) Math.Round(this.TransformToPhysical(controlToTaskview.Transform(new Point(placeholderLeft, 0)).X, 0).X),
+				Top = (int) Math.Round(this.TransformToPhysical(0, controlToTaskview.Transform(new Point(0, placeholderTop)).Y).Y),
+				Right = (int) Math.Round(this.TransformToPhysical(controlToTaskview.Transform(new Point(placeholderRight, 0)).X, 0).X),
+				Bottom = (int) Math.Round(this.TransformToPhysical(0, controlToTaskview.Transform(new Point(0, placeholderBottom)).Y).Y)
+			};
+
+			var scaleFactor = default(double);
+			var thumbnailHeight = default(double);
+			var thumbnailWidth = default(double);
+			var maxWidth = (double) physicalBounds.Right - physicalBounds.Left;
+			var maxHeight = (double) physicalBounds.Bottom - physicalBounds.Top;
+			var placeholderRatio = maxWidth / maxHeight;
+			var windowRatio = (double) size.X / size.Y;
+
+			if (windowRatio < placeholderRatio)
+			{
+				thumbnailHeight = maxHeight;
+				scaleFactor = thumbnailHeight / size.Y;
+				thumbnailWidth = size.X * scaleFactor;
+			}
+			else
+			{
+				thumbnailWidth = maxWidth;
+				scaleFactor = thumbnailWidth / size.X;
+				thumbnailHeight = size.Y * scaleFactor;
+			}
+
+			var widthDifference = maxWidth - thumbnailWidth;
+			var heightDifference = maxHeight - thumbnailHeight;
+
+			return new Thumbnail.Rectangle
+			{
+				Left = (int) Math.Round(physicalBounds.Left + (widthDifference / 2)),
+				Top = (int) Math.Round(physicalBounds.Top + (heightDifference / 2)),
+				Right = (int) Math.Round(physicalBounds.Right - (widthDifference / 2)),
+				Bottom = (int) Math.Round(physicalBounds.Bottom - (heightDifference / 2))
+			};
+		}
+
 		private void InitializeControl()
 		{
 			Icon.Content = IconResourceLoader.Load(window.Icon);
+			IsVisibleChanged += TaskViewWindowControl_IsVisibleChanged;
+			Loaded += (o, args) => Update();
 			Title.Text = window.Title;
-
+			window.IconChanged += Window_IconChanged;
-			window.IconChanged += Instance_IconChanged;
+			window.TitleChanged += Window_TitleChanged;
-			window.TitleChanged += Instance_TitleChanged;
-		}
-
-		private void Instance_TitleChanged(string title)
-		{
-			Dispatcher.InvokeAsync(() => Title.Text = title);
-		}
-
-		private void Instance_IconChanged(IconResource icon)
-		{
-			Dispatcher.InvokeAsync(() => Icon.Content = IconResourceLoader.Load(window.Icon));
 		}
 	}
 }

SafeExamBrowser.UserInterface.Desktop/SafeExamBrowser.UserInterface.Desktop.csproj

@@ -142,8 +142,8 @@
     <Compile Include="Controls\TaskbarWirelessNetworkControl.xaml.cs">
       <DependentUpon>TaskbarWirelessNetworkControl.xaml</DependentUpon>
     </Compile>
-    <Compile Include="Controls\TaskViewWindowControl.xaml.cs">
+    <Compile Include="Controls\TaskviewWindowControl.xaml.cs">
-      <DependentUpon>TaskViewWindowControl.xaml</DependentUpon>
+      <DependentUpon>TaskviewWindowControl.xaml</DependentUpon>
     </Compile>
     <Compile Include="LockScreen.xaml.cs">
       <DependentUpon>LockScreen.xaml</DependentUpon>
@@ -161,8 +161,8 @@
     <Compile Include="SplashScreen.xaml.cs">
       <DependentUpon>SplashScreen.xaml</DependentUpon>
     </Compile>
-    <Compile Include="TaskView.xaml.cs">
+    <Compile Include="Taskview.xaml.cs">
-      <DependentUpon>TaskView.xaml</DependentUpon>
+      <DependentUpon>Taskview.xaml</DependentUpon>
     </Compile>
     <Compile Include="UserInterfaceFactory.cs" />
     <Compile Include="ViewModels\DateTimeViewModel.cs" />
@@ -317,7 +317,7 @@
       <Generator>MSBuild:Compile</Generator>
       <SubType>Designer</SubType>
     </Resource>
-    <Page Include="Controls\TaskViewWindowControl.xaml">
+    <Page Include="Controls\TaskviewWindowControl.xaml">
       <SubType>Designer</SubType>
       <Generator>MSBuild:Compile</Generator>
     </Page>
@@ -325,7 +325,7 @@
       <SubType>Designer</SubType>
       <Generator>MSBuild:Compile</Generator>
     </Page>
-    <Page Include="TaskView.xaml">
+    <Page Include="Taskview.xaml">
       <SubType>Designer</SubType>
       <Generator>MSBuild:Compile</Generator>
     </Page>

SafeExamBrowser.UserInterface.Desktop/TaskView.xaml

@@ -1,11 +1,11 @@
-<Window x:Class="SafeExamBrowser.UserInterface.Desktop.TaskView"
+<Window x:Class="SafeExamBrowser.UserInterface.Desktop.Taskview"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
         xmlns:local="clr-namespace:SafeExamBrowser.UserInterface.Desktop"
         mc:Ignorable="d" AllowsTransparency="True" Background="{DynamicResource BackgroundTransparentBrush}" BorderBrush="DodgerBlue" BorderThickness="1"
-        Title="TaskView" Topmost="True" Height="450" SizeToContent="WidthAndHeight" Width="800" WindowStartupLocation="CenterScreen" WindowStyle="None">
+        Title="Taskview" Topmost="True" Height="450" SizeToContent="WidthAndHeight" Width="800" WindowStartupLocation="CenterScreen" WindowStyle="None">
     <Window.Resources>
         <ResourceDictionary>
             <ResourceDictionary.MergedDictionaries>

SafeExamBrowser.UserInterface.Desktop/TaskView.xaml.cs

@@ -11,24 +11,28 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Windows;
 using System.Windows.Controls;
+using System.Windows.Interop;
 using SafeExamBrowser.Applications.Contracts;
 using SafeExamBrowser.UserInterface.Contracts.Shell;
 using SafeExamBrowser.UserInterface.Desktop.Controls;
 
 namespace SafeExamBrowser.UserInterface.Desktop
 {
-	public partial class TaskView : Window, ITaskView
+	public partial class Taskview : Window, ITaskView
 	{
 		private IList<IApplication> applications;
-		private LinkedListNode<TaskViewWindowControl> current;
+		private LinkedListNode<TaskviewWindowControl> current;
-		private LinkedList<TaskViewWindowControl> controls;
+		private LinkedList<TaskviewWindowControl> controls;
 
-		public TaskView()
+		internal IntPtr Handle { get; private set; }
+
+		public Taskview()
 		{
 			applications = new List<IApplication>();
-			controls = new LinkedList<TaskViewWindowControl>();
+			controls = new LinkedList<TaskviewWindowControl>();
 
 			InitializeComponent();
+			InitializeTaskview();
 		}
 
 		public void Add(IApplication application)
@@ -66,9 +70,21 @@ namespace SafeExamBrowser.UserInterface.Desktop
 
 		private void ActivateAndHide()
 		{
-			Activate();
+			if (IsVisible)
-			current?.Value.Activate();
+			{
-			Hide();
+				Activate();
+				current?.Value.Activate();
+				Hide();
+			}
+		}
+
+		private void InitializeTaskview()
+		{
+			Loaded += (o, args) =>
+			{
+				Handle = new WindowInteropHelper(this).Handle;
+				Update();
+			};
 		}
 
 		private void SelectNext()
@@ -106,31 +122,37 @@ namespace SafeExamBrowser.UserInterface.Desktop
 
 		private void Update()
 		{
-			var windows = new Stack<IApplicationWindow>();
+			ClearTaskview();
+			LoadControls();
+			UpdateLocation();
+		}
 
-			foreach (var application in applications)
+		private void ClearTaskview()
+		{
+			foreach (var control in controls)
 			{
-				foreach (var window in application.GetWindows())
+				control.Destroy();
-				{
-					windows.Push(window);
-				}
 			}
 
-			var max = Math.Ceiling(Math.Sqrt(windows.Count));
-
 			controls.Clear();
 			Rows.Children.Clear();
+		}
 
-			for (var rowCount = 0; rowCount < max && windows.Any(); rowCount++)
+		private void LoadControls()
+		{
+			var windows = GetAllWindows();
+			var maxColumns = Math.Ceiling(Math.Sqrt(windows.Count));
+
+			while (windows.Any())
 			{
 				var row = new StackPanel { Orientation = Orientation.Horizontal, HorizontalAlignment = HorizontalAlignment.Center };
 
 				Rows.Children.Add(row);
 
-				for (var columnIndex = 0; columnIndex < max && windows.Any(); columnIndex++)
+				for (var column = 0; column < maxColumns && windows.Any(); column++)
 				{
 					var window = windows.Pop();
-					var control = new TaskViewWindowControl(window);
+					var control = new TaskviewWindowControl(window, this);
 
 					controls.AddLast(control);
 					row.Children.Add(control);
@@ -139,16 +161,36 @@ namespace SafeExamBrowser.UserInterface.Desktop
 
 			current = controls.First;
 			current?.Value.Select();
+		}
 
-			UpdateLayout();
+		private void UpdateLocation()
+		{
+			if (controls.Any())
+			{
+				UpdateLayout();
 
-			Left = (SystemParameters.WorkArea.Width - Width) / 2 + SystemParameters.WorkArea.Left;
+				Left = (SystemParameters.WorkArea.Width - Width) / 2 + SystemParameters.WorkArea.Left;
-			Top = (SystemParameters.WorkArea.Height - Height) / 2 + SystemParameters.WorkArea.Top;
+				Top = (SystemParameters.WorkArea.Height - Height) / 2 + SystemParameters.WorkArea.Top;
-
+			}
-			if (!controls.Any())
+			else
 			{
 				Hide();
 			}
 		}
+
+		private Stack<IApplicationWindow> GetAllWindows()
+		{
+			var stack = new Stack<IApplicationWindow>();
+
+			foreach (var application in applications)
+			{
+				foreach (var window in application.GetWindows())
+				{
+					stack.Push(window);
+				}
+			}
+
+			return stack;
+		}
 	}
 }

SafeExamBrowser.UserInterface.Mobile/BrowserWindow.xaml.cs

@@ -12,6 +12,7 @@ using System.Threading.Tasks;
 using System.Windows;
 using System.Windows.Controls.Primitives;
 using System.Windows.Input;
+using System.Windows.Interop;
 using System.Windows.Media;
 using System.Windows.Media.Imaging;
 using SafeExamBrowser.Applications.Contracts.Resources.Icons;
@@ -40,6 +41,7 @@ namespace SafeExamBrowser.UserInterface.Mobile
 
 		public bool CanNavigateBackwards { set => Dispatcher.Invoke(() => BackwardButton.IsEnabled = value); }
 		public bool CanNavigateForwards { set => Dispatcher.Invoke(() => ForwardButton.IsEnabled = value); }
+		public IntPtr Handle { get; private set; }
 
 		public event AddressChangedEventHandler AddressChanged;
 		public event ActionRequestedEventHandler BackwardNavigationRequested;
@@ -157,6 +159,8 @@ namespace SafeExamBrowser.UserInterface.Mobile
 
 		private void BrowserWindow_Loaded(object sender, RoutedEventArgs e)
 		{
+			Handle = new WindowInteropHelper(this).Handle;
+
 			if (isMainWindow)
 			{
 				WindowUtility.DisableCloseButtonFor(this);

SafeExamBrowser.UserInterface.Shared/SafeExamBrowser.UserInterface.Shared.csproj

@@ -73,6 +73,7 @@
       <SubType>Code</SubType>
     </Compile>
     <Compile Include="Utilities\IconResourceLoader.cs" />
+    <Compile Include="Utilities\Thumbnail.cs" />
     <Compile Include="Utilities\VisualExtensions.cs" />
     <Compile Include="Utilities\WindowUtility.cs" />
   </ItemGroup>

SafeExamBrowser.UserInterface.Shared/Utilities/Thumbnail.cs

@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2019 ETH Zürich, Educational Development and Technology (LET)
+ * 
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+using System;
+using System.Runtime.InteropServices;
+
+namespace SafeExamBrowser.UserInterface.Shared.Utilities
+{
+	/// <remarks>
+	/// See https://docs.microsoft.com/en-us/windows/win32/dwm/thumbnail-ovw.
+	/// </remarks>
+	public static class Thumbnail
+	{
+		public const int DWM_TNP_VISIBLE = 0x8;
+		public const int DWM_TNP_OPACITY = 0x4;
+		public const int DWM_TNP_RECTDESTINATION = 0x1;
+		public const int S_OK = 0;
+
+		[DllImport("dwmapi.dll")]
+		public static extern int DwmQueryThumbnailSourceSize(IntPtr thumbnail, out Size size);
+
+		[DllImport("dwmapi.dll")]
+		public static extern int DwmRegisterThumbnail(IntPtr destinationWindow, IntPtr sourceWindow, out IntPtr thumbnail);
+
+		[DllImport("dwmapi.dll")]
+		public static extern int DwmUnregisterThumbnail(IntPtr thumbnail);
+
+		[DllImport("dwmapi.dll")]
+		public static extern int DwmUpdateThumbnailProperties(IntPtr thumbnail, ref Properties properties);
+
+		[StructLayout(LayoutKind.Sequential)]
+		public struct Properties
+		{
+			public int Flags;
+			public Rectangle Destination;
+			public Rectangle Source;
+			public byte Opacity;
+			public bool Visible;
+			public bool SourceClientAreaOnly;
+		}
+
+		[StructLayout(LayoutKind.Sequential)]
+		public struct Size
+		{
+			public int X;
+			public int Y;
+		}
+
+		[StructLayout(LayoutKind.Sequential)]
+		public struct Rectangle
+		{
+			public int Left;
+			public int Top;
+			public int Right;
+			public int Bottom;
+		}
+	}
+}

SafeExamBrowser.WindowsApi/ProcessFactory.cs

@@ -72,29 +72,6 @@ namespace SafeExamBrowser.WindowsApi
 			return process;
 		}
 
-		private System.Diagnostics.Process StartOnDesktop(string path, params string[] args)
-		{
-			var commandLine = $"{'"' + path + '"'} {string.Join(" ", args)}";
-			var processInfo = new PROCESS_INFORMATION();
-			var startupInfo = new STARTUPINFO();
-
-			startupInfo.cb = Marshal.SizeOf(startupInfo);
-			startupInfo.lpDesktop = StartupDesktop?.Name;
-
-			var success = Kernel32.CreateProcess(null, commandLine, IntPtr.Zero, IntPtr.Zero, true, Constant.NORMAL_PRIORITY_CLASS, IntPtr.Zero, null, ref startupInfo, ref processInfo);
-
-			if (success)
-			{
-				return System.Diagnostics.Process.GetProcessById(processInfo.dwProcessId);
-			}
-
-			var errorCode = Marshal.GetLastWin32Error();
-
-			logger.Error($"Failed to start process '{path}' on desktop '{StartupDesktop}'! Error code: {errorCode}.");
-
-			throw new Win32Exception(errorCode);
-		}
-
 		public bool TryGetById(int id, out IProcess process)
 		{
 			var raw = System.Diagnostics.Process.GetProcesses().FirstOrDefault(p => p.Id == id);
@@ -183,5 +160,28 @@ namespace SafeExamBrowser.WindowsApi
 		{
 			return logger.CloneFor($"{nameof(Process)} '{name}' ({process.Id})");
 		}
+
+		private System.Diagnostics.Process StartOnDesktop(string path, params string[] args)
+		{
+			var commandLine = $"{'"' + path + '"'} {string.Join(" ", args)}";
+			var processInfo = new PROCESS_INFORMATION();
+			var startupInfo = new STARTUPINFO();
+
+			startupInfo.cb = Marshal.SizeOf(startupInfo);
+			startupInfo.lpDesktop = StartupDesktop?.Name;
+
+			var success = Kernel32.CreateProcess(null, commandLine, IntPtr.Zero, IntPtr.Zero, true, Constant.NORMAL_PRIORITY_CLASS, IntPtr.Zero, null, ref startupInfo, ref processInfo);
+
+			if (success)
+			{
+				return System.Diagnostics.Process.GetProcessById(processInfo.dwProcessId);
+			}
+
+			var errorCode = Marshal.GetLastWin32Error();
+
+			logger.Error($"Failed to start process '{path}' on desktop '{StartupDesktop}'! Error code: {errorCode}.");
+
+			throw new Win32Exception(errorCode);
+		}
 	}
 }