SEBWIN-219: Implemented basic shutdown mechanism.

SafeExamBrowser.Client/Behaviour/ClientController.cs

@@ -26,6 +26,8 @@ namespace SafeExamBrowser.Client.Behaviour
 		private ITaskbar taskbar;
 		private IWindowMonitor windowMonitor;
 
+		public IClientHost ClientHost { private get; set; }
+
 		public ClientController(
 			IDisplayMonitor displayMonitor,
 			ILogger logger,
@@ -44,34 +46,46 @@ namespace SafeExamBrowser.Client.Behaviour
 			this.windowMonitor = windowMonitor;
 		}
 
+		public bool TryStart()
+		{
+			var success = operations.TryPerform();
+
+			// TODO
+
+			if (success)
+			{
+				RegisterEvents();
+				runtime.InformClientReady();
+			}
+
+			return success;
+		}
+
 		public void Terminate()
 		{
-			displayMonitor.DisplayChanged -= DisplayMonitor_DisplaySettingsChanged;
+			DeregisterEvents();
-			processMonitor.ExplorerStarted -= ProcessMonitor_ExplorerStarted;
-			windowMonitor.WindowChanged -= WindowMonitor_WindowChanged;
 
 			// TODO
 
 			operations.TryRevert();
 		}
 
-		public bool TryStart()
+		private void RegisterEvents()
 		{
+			ClientHost.Shutdown += ClientHost_Shutdown;
+			displayMonitor.DisplayChanged += DisplayMonitor_DisplaySettingsChanged;
+			processMonitor.ExplorerStarted += ProcessMonitor_ExplorerStarted;
+			taskbar.QuitButtonClicked += Taskbar_QuitButtonClicked;
+			windowMonitor.WindowChanged += WindowMonitor_WindowChanged;
+		}
 
-			// TODO
+		private void DeregisterEvents()
-
+		{
-			var success = operations.TryPerform();
+			ClientHost.Shutdown -= ClientHost_Shutdown;
-
+			displayMonitor.DisplayChanged -= DisplayMonitor_DisplaySettingsChanged;
-			if (success)
+			processMonitor.ExplorerStarted -= ProcessMonitor_ExplorerStarted;
-			{
+			taskbar.QuitButtonClicked -= Taskbar_QuitButtonClicked;
-				displayMonitor.DisplayChanged += DisplayMonitor_DisplaySettingsChanged;
+			windowMonitor.WindowChanged -= WindowMonitor_WindowChanged;
-				processMonitor.ExplorerStarted += ProcessMonitor_ExplorerStarted;
-				windowMonitor.WindowChanged += WindowMonitor_WindowChanged;
-
-				runtime.InformClientReady();
-			}
-
-			return success;
 		}
 
 		private void DisplayMonitor_DisplaySettingsChanged()
@@ -94,6 +108,24 @@ namespace SafeExamBrowser.Client.Behaviour
 			logger.Info("Desktop successfully restored.");
 		}
 
+		private void ClientHost_Shutdown()
+		{
+			// TODO: Better use callback to Application.Shutdown() as in runtime?
+			taskbar.Close();
+		}
+
+		private void Taskbar_QuitButtonClicked()
+		{
+			// TODO: MessageBox asking whether user really wants to quit -> args.Cancel
+
+			var acknowledged = runtime.RequestShutdown();
+
+			if (!acknowledged)
+			{
+				logger.Warn("The runtime did not acknowledge the shutdown request!");
+			}
+		}
+
 		private void WindowMonitor_WindowChanged(IntPtr window)
 		{
 			var allowed = processMonitor.BelongsToAllowedProcess(window);

SafeExamBrowser.Client/Communication/ClientHost.cs

@@ -21,6 +21,8 @@ namespace SafeExamBrowser.Client.Communication
 
 		public Guid StartupToken { private get; set; }
 
+		public event CommunicationEventHandler Shutdown;
+
 		public ClientHost(string address, ILogger logger, int processId) : base(address, logger)
 		{
 			this.processId = processId;
@@ -49,6 +51,9 @@ namespace SafeExamBrowser.Client.Communication
 			{
 				case SimpleMessagePurport.Authenticate:
 					return new AuthenticationResponse { ProcessId = processId };
+				case SimpleMessagePurport.Shutdown:
+					Shutdown?.Invoke();
+					return new SimpleResponse(SimpleResponsePurport.Acknowledged);
 			}
 
 			return new SimpleResponse(SimpleResponsePurport.UnknownMessage);

SafeExamBrowser.Client/CompositionRoot.cs

@@ -102,6 +102,7 @@ namespace SafeExamBrowser.Client
 
 		internal void LogShutdownInformation()
 		{
+			logger?.Log(string.Empty);
 			logger?.Log($"# Client instance terminated at {DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss.fff")}");
 		}
 
@@ -153,6 +154,7 @@ namespace SafeExamBrowser.Client
 			var operation = new CommunicationOperation(host, logger);
 
 			host.StartupToken = startupToken;
+			ClientController.ClientHost = host;
 
 			return operation;
 		}

SafeExamBrowser.Configuration/ConfigurationRepository.cs

@@ -73,6 +73,12 @@ namespace SafeExamBrowser.Configuration
 			};
 
 			settings.Browser.StartUrl = "https://www.duckduckgo.com";
+			settings.Browser.AllowAddressBar = true;
+			settings.Browser.AllowBackwardNavigation = true;
+			settings.Browser.AllowDeveloperConsole = true;
+			settings.Browser.AllowForwardNavigation = true;
+			settings.Browser.AllowReloading = true;
+
 			settings.Taskbar.AllowApplicationLog = true;
 			settings.Taskbar.AllowKeyboardLayout = true;
 			settings.Taskbar.AllowWirelessNetwork = true;

SafeExamBrowser.Contracts/Behaviour/IClientController.cs

@@ -6,11 +6,18 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
+using SafeExamBrowser.Contracts.Communication;
+
 namespace SafeExamBrowser.Contracts.Behaviour
 {
 	// TODO: Interface really needed?!
 	public interface IClientController
 	{
+		/// <summary>
+		/// The client host used for communication handling.
+		/// </summary>
+		IClientHost ClientHost { set; }
+
 		/// <summary>
 		/// Reverts any changes, releases all used resources and terminates the client.
 		/// </summary>

SafeExamBrowser.Contracts/Communication/IClientHost.cs

@@ -16,5 +16,10 @@ namespace SafeExamBrowser.Contracts.Communication
 		/// The startup token used for initial authentication.
 		/// </summary>
 		Guid StartupToken { set; }
+
+		/// <summary>
+		/// Event fired when the runtime commands the client to shutdown.
+		/// </summary>
+		event CommunicationEventHandler Shutdown;
 	}
 }

SafeExamBrowser.Contracts/Communication/IClientProxy.cs

@@ -12,6 +12,11 @@ namespace SafeExamBrowser.Contracts.Communication
 {
 	public interface IClientProxy : ICommunicationProxy
 	{
+		/// <summary>
+		/// Instructs the client to initiate its shutdown procedure.
+		/// </summary>
+		void InitiateShutdown();
+
 		/// <summary>
 		/// Instructs the client to submit its authentication data.
 		/// </summary>

SafeExamBrowser.Contracts/Communication/IRuntimeHost.cs

@@ -17,9 +17,19 @@ namespace SafeExamBrowser.Contracts.Communication
 		/// </summary>
 		Guid StartupToken { set; }
 
+		/// <summary>
+		/// Event fired when the client disconnected from the runtime.
+		/// </summary>
+		event CommunicationEventHandler ClientDisconnected;
+
 		/// <summary>
 		/// Event fired once the client has signaled that it is ready to operate.
 		/// </summary>
 		event CommunicationEventHandler ClientReady;
+
+		/// <summary>
+		/// Event fired when the client requests to shut down the application.
+		/// </summary>
+		event CommunicationEventHandler ShutdownRequested;
 	}
 }

SafeExamBrowser.Contracts/Communication/IRuntimeProxy.cs

@@ -15,11 +15,18 @@ namespace SafeExamBrowser.Contracts.Communication
 		/// <summary>
 		/// Retrieves the application configuration from the runtime.
 		/// </summary>
+		/// <exception cref="System.ServiceModel.CommunicationException">If the configuration could not be retrieved.</exception>
 		ClientConfiguration GetConfiguration();
 
 		/// <summary>
 		/// Informs the runtime that the client is ready.
 		/// </summary>
+		/// <exception cref="System.ServiceModel.CommunicationException">If the runtime did not acknowledge the status update.</exception>
 		void InformClientReady();
+
+		/// <summary>
+		/// Requests the runtime to shut down the application. Returns <c>true</c> if the request was acknowledged, otherwise <c>false</c>.
+		/// </summary>
+		bool RequestShutdown();
 	}
 }

SafeExamBrowser.Contracts/Communication/Messages/SimpleMessagePurport.cs

@@ -27,5 +27,15 @@ namespace SafeExamBrowser.Contracts.Communication.Messages
 		/// Sent from the client to the runtime to ask for the client configuration.
 		/// </summary>
 		ConfigurationNeeded,
+
+		/// <summary>
+		/// Sent from the client to the runtime to request shutting down the application.
+		/// </summary>
+		RequestShutdown,
+
+		/// <summary>
+		/// Sent form the runtime to the client to command the latter to shut itself down.
+		/// </summary>
+		Shutdown
 	}
 }

SafeExamBrowser.Contracts/UserInterface/Taskbar/ITaskbar.cs

@@ -8,8 +8,15 @@
 
 namespace SafeExamBrowser.Contracts.UserInterface.Taskbar
 {
+	public delegate void QuitButtonClickedEventHandler();
+
 	public interface ITaskbar
 	{
+		/// <summary>
+		/// Event fired when the user clicked the quit button in the taskbar.
+		/// </summary>
+		event QuitButtonClickedEventHandler QuitButtonClicked;
+
 		/// <summary>
 		/// Adds the given application button to the taskbar.
 		/// </summary>
@@ -25,6 +32,11 @@ namespace SafeExamBrowser.Contracts.UserInterface.Taskbar
 		/// </summary>
 		void AddSystemControl(ISystemControl control);
 
+		/// <summary>
+		/// Closes the taskbar.
+		/// </summary>
+		void Close();
+
 		/// <summary>
 		/// Returns the absolute height of the taskbar (i.e. in physical pixels).
 		/// </summary>

SafeExamBrowser.Contracts/WindowsApi/IProcess.cs

@@ -8,11 +8,28 @@
 
 namespace SafeExamBrowser.Contracts.WindowsApi
 {
+	public delegate void ProcessTerminatedEventHandler(int exitCode);
+
 	public interface IProcess
 	{
+		/// <summary>
+		/// Indicates whether the process has been terminated.
+		/// </summary>
+		bool HasTerminated { get; }
+
 		/// <summary>
 		/// The process identifier.
 		/// </summary>
 		int Id { get; }
+
+		/// <summary>
+		/// Event fired when the process has terminated.
+		/// </summary>
+		event ProcessTerminatedEventHandler Terminated;
+
+		/// <summary>
+		/// Immediately terminates the process.
+		/// </summary>
+		void Kill();
 	}
 }

SafeExamBrowser.Core/Communication/BaseHost.cs

@@ -97,9 +97,7 @@ namespace SafeExamBrowser.Core.Communication
 		{
 			lock (@lock)
 			{
-				Response response = null;
+				var response = default(Response);
-
-				logger.Debug($"Received message '{ToString(message)}'.");
 
 				if (IsAuthorized(message?.CommunicationToken))
 				{
@@ -113,7 +111,7 @@ namespace SafeExamBrowser.Core.Communication
 					}
 				}
 
-				logger.Debug($"Sending response '{ToString(response)}'.");
+				logger.Debug($"Received message '{ToString(message)}', sending response '{ToString(response)}'.");
 
 				return response;
 			}

SafeExamBrowser.Core/Communication/BaseProxy.cs

@@ -80,6 +80,16 @@ namespace SafeExamBrowser.Core.Communication
 			return Send(new SimpleMessage(purport));
 		}
 
+		protected string ToString(Message message)
+		{
+			return message != null ? message.ToString() : "<null>";
+		}
+
+		protected string ToString(Response response)
+		{
+			return response != null ? response.ToString() : "<null>";
+		}
+
 		private void BaseProxy_Closed(object sender, EventArgs e)
 		{
 			Logger.Debug("Communication channel has been closed.");
@@ -122,15 +132,5 @@ namespace SafeExamBrowser.Core.Communication
 		{
 			return channel == null ? "null" : $"in state '{(channel as ICommunicationObject).State}'";
 		}
-
-		private string ToString(Message message)
-		{
-			return message != null ? message.ToString() : "<null>";
-		}
-
-		private string ToString(Response response)
-		{
-			return response != null ? response.ToString() : "<null>";
-		}
 	}
 }

SafeExamBrowser.Core/Communication/ClientProxy.cs

@@ -19,6 +19,16 @@ namespace SafeExamBrowser.Core.Communication
 		{
 		}
 
+		public void InitiateShutdown()
+		{
+			var response = Send(SimpleMessagePurport.Shutdown);
+
+			if (response is SimpleResponse simpleMessage && simpleMessage.Purport == SimpleResponsePurport.Acknowledged)
+			{
+				// TODO
+			}
+		}
+
 		public AuthenticationResponse RequestAuthentication()
 		{
 			var response = Send(SimpleMessagePurport.Authenticate);

SafeExamBrowser.Core/Communication/RuntimeProxy.cs

@@ -6,6 +6,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
+using System.ServiceModel;
 using SafeExamBrowser.Contracts.Communication;
 using SafeExamBrowser.Contracts.Communication.Messages;
 using SafeExamBrowser.Contracts.Communication.Responses;
@@ -22,12 +23,37 @@ namespace SafeExamBrowser.Core.Communication
 
 		public ClientConfiguration GetConfiguration()
 		{
-			return ((ConfigurationResponse) Send(SimpleMessagePurport.ConfigurationNeeded)).Configuration;
+			var response = Send(SimpleMessagePurport.ConfigurationNeeded);
+
+			if (response is ConfigurationResponse configurationResponse)
+			{
+				return configurationResponse.Configuration;
+			}
+
+			throw new CommunicationException($"Could not retrieve client configuration! Received: {ToString(response)}.");
 		}
 
 		public void InformClientReady()
 		{
-			Send(SimpleMessagePurport.ClientIsReady);
+			var response = Send(SimpleMessagePurport.ClientIsReady);
+
+			if (!IsAcknowledgeResponse(response))
+			{
+				throw new CommunicationException($"Runtime did not acknowledge that client is ready! Response: {ToString(response)}.");
+			}
+		}
+
+		public bool RequestShutdown()
+		{
+			var response = Send(SimpleMessagePurport.RequestShutdown);
+			var acknowledged = IsAcknowledgeResponse(response);
+
+			return acknowledged;
+		}
+
+		private bool IsAcknowledgeResponse(Response response)
+		{
+			return response is SimpleResponse simpleResponse && simpleResponse.Purport == SimpleResponsePurport.Acknowledged;
 		}
 	}
 }

SafeExamBrowser.Core/Communication/ServiceProxy.cs

@@ -58,7 +58,7 @@ namespace SafeExamBrowser.Core.Communication
 				return;
 			}
 
-			// TODO
+			// TODO: Send(new StopSessionMessage { SessionId = sessionId });
 		}
 
 		private bool IgnoreOperation(string operationName)

SafeExamBrowser.Runtime/Behaviour/Operations/SessionSequenceOperation.cs

@@ -20,6 +20,8 @@ namespace SafeExamBrowser.Runtime.Behaviour.Operations
 {
 	internal abstract class SessionSequenceOperation : IOperation
 	{
+		private const int TEN_SECONDS = 10000;
+
 		private bool sessionRunning;
 		private IClientProxy client;
 		private IConfigurationRepository configuration;
@@ -68,7 +70,6 @@ namespace SafeExamBrowser.Runtime.Behaviour.Operations
 			}
 			catch (Exception e)
 			{
-				service.StopSession(session.Id);
 				logger.Error("Failed to start client!", e);
 			}
 
@@ -80,6 +81,7 @@ namespace SafeExamBrowser.Runtime.Behaviour.Operations
 			{
 				Abort = true;
 				logger.Info($"Failed to start new session! Aborting...");
+				service.StopSession(session.Id);
 			}
 		}
 
@@ -92,8 +94,14 @@ namespace SafeExamBrowser.Runtime.Behaviour.Operations
 
 				service.StopSession(session.Id);
 
-				// TODO:
+				try
-				// - Terminate client (or does it terminate itself?)
+				{
+					StopClient();
+				}
+				catch (Exception e)
+				{
+					logger.Error("Failed to terminate client!", e);
+				}
 
 				sessionRunning = false;
 				logger.Info($"Successfully stopped session with identifier '{session.Id}'.");
@@ -102,9 +110,7 @@ namespace SafeExamBrowser.Runtime.Behaviour.Operations
 
 		private void StartClient()
 		{
-			const int TEN_SECONDS = 10000;
+			var clientReady = false;
-
-			var clientStarted = false;
 			var clientReadyEvent = new AutoResetEvent(false);
 			var clientReadyEventHandler = new CommunicationEventHandler(() => clientReadyEvent.Set());
 			var clientExecutable = configuration.RuntimeInfo.ClientExecutablePath;
@@ -113,13 +119,14 @@ namespace SafeExamBrowser.Runtime.Behaviour.Operations
 			var token = session.StartupToken.ToString("D");
 
 			runtimeHost.ClientReady += clientReadyEventHandler;
-			session.ClientProcess = processFactory.StartNew(clientExecutable, clientLogFile, hostUri, token);
 
-			clientStarted = clientReadyEvent.WaitOne(TEN_SECONDS);
+			session.ClientProcess = processFactory.StartNew(clientExecutable, clientLogFile, hostUri, token);
+			clientReady = clientReadyEvent.WaitOne(TEN_SECONDS);
+
 			runtimeHost.ClientReady -= clientReadyEventHandler;
 
 			// TODO: Check if client process alive!
-			if (clientStarted)
+			if (clientReady)
 			{
 				if (client.Connect(session.StartupToken))
 				{
@@ -145,5 +152,71 @@ namespace SafeExamBrowser.Runtime.Behaviour.Operations
 				logger.Error($"Failed to start client within {TEN_SECONDS / 1000} seconds!");
 			}
 		}
+
+		private void StopClient()
+		{
+			var disconnected = false;
+			var disconnectedEvent = new AutoResetEvent(false);
+			var disconnectedEventHandler = new CommunicationEventHandler(() => disconnectedEvent.Set());
+
+			var terminated = false;
+			var terminatedEvent = new AutoResetEvent(false);
+			var terminatedEventHandler = new ProcessTerminatedEventHandler((_) => terminatedEvent.Set());
+
+			runtimeHost.ClientDisconnected += disconnectedEventHandler;
+			session.ClientProcess.Terminated += terminatedEventHandler;
+
+			client.InitiateShutdown();
+			client.Disconnect();
+
+			disconnected = disconnectedEvent.WaitOne(TEN_SECONDS);
+			terminated = terminatedEvent.WaitOne(TEN_SECONDS);
+
+			runtimeHost.ClientDisconnected -= disconnectedEventHandler;
+			session.ClientProcess.Terminated -= terminatedEventHandler;
+
+			if (disconnected && terminated)
+			{
+				logger.Info("Client has been successfully terminated.");
+			}
+			else
+			{
+				if (!disconnected)
+				{
+					logger.Error($"Client failed to disconnect within {TEN_SECONDS / 1000} seconds!");
+				}
+				else if (!terminated)
+				{
+					logger.Error($"Client failed to terminate within {TEN_SECONDS / 1000} seconds!");
+				}
+
+				KillClient();
+			}
+		}
+
+		private void KillClient(int attempt = 0)
+		{
+			const int MAX_ATTEMPTS = 5;
+
+			if (attempt == MAX_ATTEMPTS)
+			{
+				logger.Error($"Failed to kill client process within {MAX_ATTEMPTS} attempts!");
+
+				return;
+			}
+
+			logger.Info($"Killing client process with ID = {session.ClientProcess.Id}.");
+			session.ClientProcess.Kill();
+
+			if (session.ClientProcess.HasTerminated)
+			{
+				logger.Info("Client process has terminated.");
+			}
+			else
+			{
+				logger.Warn("Failed to kill client process. Trying again...");
+				KillClient(attempt++);
+			}
+		}
 	}
 }

SafeExamBrowser.Runtime/Behaviour/RuntimeController.cs

@@ -80,6 +80,7 @@ namespace SafeExamBrowser.Runtime.Behaviour
 				logger.Subscribe(runtimeWindow);
 
 				splashScreen.Hide();
+				runtimeHost.ShutdownRequested += RuntimeHost_ShutdownRequested;
 
 				StartSession(true);
 			}
@@ -169,5 +170,11 @@ namespace SafeExamBrowser.Runtime.Behaviour
 				// TODO
 			}
 		}
+
+		private void RuntimeHost_ShutdownRequested()
+		{
+			logger.Info("Received shutdown request from client application.");
+			shutdown.Invoke();
+		}
 	}
 }

SafeExamBrowser.Runtime/Communication/RuntimeHost.cs

@@ -7,6 +7,7 @@
  */
 
 using System;
+using System.Threading.Tasks;
 using SafeExamBrowser.Contracts.Communication;
 using SafeExamBrowser.Contracts.Communication.Messages;
 using SafeExamBrowser.Contracts.Communication.Responses;
@@ -22,7 +23,9 @@ namespace SafeExamBrowser.Runtime.Communication
 
 		public Guid StartupToken { private get; set; }
 
+		public event CommunicationEventHandler ClientDisconnected;
 		public event CommunicationEventHandler ClientReady;
+		public event CommunicationEventHandler ShutdownRequested;
 
 		public RuntimeHost(string address, IConfigurationRepository configuration, ILogger logger) : base(address, logger)
 		{
@@ -36,7 +39,7 @@ namespace SafeExamBrowser.Runtime.Communication
 
 		protected override void OnDisconnect()
 		{
-			// TODO
+			Task.Run(() => ClientDisconnected?.Invoke());
 		}
 
 		protected override Response OnReceive(Message message)
@@ -54,6 +57,9 @@ namespace SafeExamBrowser.Runtime.Communication
 					return new SimpleResponse(SimpleResponsePurport.Acknowledged);
 				case SimpleMessagePurport.ConfigurationNeeded:
 					return new ConfigurationResponse { Configuration = configuration.BuildClientConfiguration() };
+				case SimpleMessagePurport.RequestShutdown:
+					ShutdownRequested?.Invoke();
+					return new SimpleResponse(SimpleResponsePurport.Acknowledged);
 			}
 
 			return new SimpleResponse(SimpleResponsePurport.UnknownMessage);

SafeExamBrowser.Runtime/CompositionRoot.cs

@@ -39,7 +39,7 @@ namespace SafeExamBrowser.Runtime
 			var args = Environment.GetCommandLineArgs();
 			var configuration = new ConfigurationRepository();
 			var nativeMethods = new NativeMethods();
-			Action shutdown = Application.Current.Shutdown;
+			void shutdown() => Application.Current.Dispatcher.BeginInvoke(new Action(Application.Current.Shutdown));
 
 			logger = new Logger();
 			runtimeInfo = configuration.RuntimeInfo;
@@ -75,12 +75,10 @@ namespace SafeExamBrowser.Runtime
 
 		internal void LogStartupInformation()
 		{
-			var titleLine = $"/* {runtimeInfo.ProgramTitle}, Version {runtimeInfo.ProgramVersion}{Environment.NewLine}";
+			logger.Log($"/* {runtimeInfo.ProgramTitle}, Version {runtimeInfo.ProgramVersion}");
-			var copyrightLine = $"/* {runtimeInfo.ProgramCopyright}{Environment.NewLine}";
+			logger.Log($"/* {runtimeInfo.ProgramCopyright}");
-			var emptyLine = $"/* {Environment.NewLine}";
+			logger.Log($"/* ");
-			var githubLine = $"/* Please visit https://www.github.com/SafeExamBrowser for more information.";
+			logger.Log($"/* Please visit https://www.github.com/SafeExamBrowser for more information.");
-
-			logger.Log($"{titleLine}{copyrightLine}{emptyLine}{githubLine}");
 			logger.Log(string.Empty);
 			logger.Log($"# Application started at {runtimeInfo.ApplicationStartTime.ToString("yyyy-MM-dd HH:mm:ss.fff")}");
 			logger.Log($"# Running on {systemInfo.OperatingSystemInfo}");

SafeExamBrowser.UserInterface.Classic/Controls/QuitButton.xaml.cs

@@ -9,12 +9,15 @@
 using System;
 using System.Windows;
 using System.Windows.Controls;
+using SafeExamBrowser.Contracts.UserInterface.Taskbar;
 using SafeExamBrowser.UserInterface.Classic.Utilities;
 
 namespace SafeExamBrowser.UserInterface.Classic.Controls
 {
 	public partial class QuitButton : UserControl
 	{
+		public QuitButtonClickedEventHandler Clicked;
+
 		public QuitButton()
 		{
 			InitializeComponent();
@@ -23,7 +26,7 @@ namespace SafeExamBrowser.UserInterface.Classic.Controls
 
 		private void Button_Click(object sender, RoutedEventArgs e)
 		{
-			Application.Current.MainWindow.Close();
+			Clicked?.Invoke();
 		}
 
 		private void LoadIcon()

SafeExamBrowser.UserInterface.Classic/Taskbar.xaml

@@ -25,6 +25,6 @@
         <local:DateTimeControl Grid.Column="1" Foreground="DimGray" />
         <StackPanel Grid.Column="2" x:Name="NotificationStackPanel" Margin="5,0,0,0" Orientation="Horizontal" VerticalAlignment="Stretch" />
         <StackPanel Grid.Column="3" x:Name="SystemControlStackPanel" Orientation="Horizontal" VerticalAlignment="Stretch" />
-        <local:QuitButton Grid.Column="4" />
+        <local:QuitButton Grid.Column="4" x:Name="QuitButton" />
     </Grid>
 </Window>

SafeExamBrowser.UserInterface.Classic/Taskbar.xaml.cs

@@ -6,6 +6,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
+using System.ComponentModel;
 using System.Windows;
 using SafeExamBrowser.Contracts.Logging;
 using SafeExamBrowser.Contracts.UserInterface.Taskbar;
@@ -17,14 +18,17 @@ namespace SafeExamBrowser.UserInterface.Classic
 	{
 		private ILogger logger;
 
+		public event QuitButtonClickedEventHandler QuitButtonClicked;
+
 		public Taskbar(ILogger logger)
 		{
 			InitializeComponent();
 
 			this.logger = logger;
 
-			Loaded += (o, args) => InitializeBounds();
 			Closing += Taskbar_Closing;
+			Loaded += (o, args) => InitializeBounds();
+			QuitButton.Clicked += () => QuitButtonClicked?.Invoke();
 		}
 
 		public void AddApplication(IApplicationButton button)
@@ -51,6 +55,11 @@ namespace SafeExamBrowser.UserInterface.Classic
 			}
 		}
 
+		public new void Close()
+		{
+			Dispatcher.Invoke(base.Close);
+		}
+
 		public int GetAbsoluteHeight()
 		{
 			return Dispatcher.Invoke(() =>
@@ -78,7 +87,7 @@ namespace SafeExamBrowser.UserInterface.Classic
 			});
 		}
 
-		private void Taskbar_Closing(object sender, System.ComponentModel.CancelEventArgs e)
+		private void Taskbar_Closing(object sender, CancelEventArgs e)
 		{
 			foreach (var child in SystemControlStackPanel.Children)
 			{

SafeExamBrowser.UserInterface.Windows10/Controls/QuitButton.xaml.cs

@@ -8,11 +8,14 @@
 
 using System.Windows;
 using System.Windows.Controls;
+using SafeExamBrowser.Contracts.UserInterface.Taskbar;
 
 namespace SafeExamBrowser.UserInterface.Windows10.Controls
 {
 	public partial class QuitButton : UserControl
 	{
+		public event QuitButtonClickedEventHandler Clicked;
+
 		public QuitButton()
 		{
 			InitializeComponent();
@@ -20,7 +23,7 @@ namespace SafeExamBrowser.UserInterface.Windows10.Controls
 
 		private void Button_Click(object sender, RoutedEventArgs e)
 		{
-			Application.Current.MainWindow.Close();
+			Clicked?.Invoke();
 		}
 	}
 }

SafeExamBrowser.UserInterface.Windows10/Taskbar.xaml

@@ -29,7 +29,7 @@
             <StackPanel Grid.Column="1" x:Name="NotificationStackPanel" Margin="5,0,0,0" Orientation="Horizontal" VerticalAlignment="Stretch" />
             <StackPanel Grid.Column="2" x:Name="SystemControlStackPanel" Orientation="Horizontal" VerticalAlignment="Stretch" />
             <local:DateTimeControl Grid.Column="3" />
-            <local:QuitButton Grid.Column="4" />
+            <local:QuitButton Grid.Column="4" x:Name="QuitButton" />
         </Grid>
     </Border>
 </Window>

SafeExamBrowser.UserInterface.Windows10/Taskbar.xaml.cs

@@ -6,6 +6,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
+using System.ComponentModel;
 using System.Windows;
 using SafeExamBrowser.Contracts.Logging;
 using SafeExamBrowser.Contracts.UserInterface.Taskbar;
@@ -17,6 +18,8 @@ namespace SafeExamBrowser.UserInterface.Windows10
 	{
 		private ILogger logger;
 
+		public event QuitButtonClickedEventHandler QuitButtonClicked;
+
 		public Taskbar(ILogger logger)
 		{
 			this.logger = logger;
@@ -25,6 +28,7 @@ namespace SafeExamBrowser.UserInterface.Windows10
 
 			Loaded += (o, args) => InitializeBounds();
 			Closing += Taskbar_Closing;
+			QuitButtonClicked += Taskbar_QuitButtonClicked;
 		}
 
 		public void AddApplication(IApplicationButton button)
@@ -51,6 +55,11 @@ namespace SafeExamBrowser.UserInterface.Windows10
 			}
 		}
 
+		public new void Close()
+		{
+			Dispatcher.Invoke(base.Close);
+		}
+
 		public int GetAbsoluteHeight()
 		{
 			return Dispatcher.Invoke(() =>
@@ -78,7 +87,12 @@ namespace SafeExamBrowser.UserInterface.Windows10
 			});
 		}
 
-		private void Taskbar_Closing(object sender, System.ComponentModel.CancelEventArgs e)
+		private void Taskbar_QuitButtonClicked()
+		{
+			QuitButtonClicked?.Invoke();
+		}
+
+		private void Taskbar_Closing(object sender, CancelEventArgs e)
 		{
 			foreach (var child in SystemControlStackPanel.Children)
 			{

SafeExamBrowser.WindowsApi/Process.cs

@@ -14,14 +14,33 @@ namespace SafeExamBrowser.WindowsApi
 	{
 		private System.Diagnostics.Process process;
 
+		public event ProcessTerminatedEventHandler Terminated;
+
 		public int Id
 		{
 			get { return process.Id; }
 		}
 
+		public bool HasTerminated
+		{
+			get { return process.HasExited; }
+		}
+
 		public Process(int id)
 		{
 			process = System.Diagnostics.Process.GetProcessById(id);
+			process.Exited += Process_Exited;
+			process.EnableRaisingEvents = true;
+		}
+
+		public void Kill()
+		{
+			process.Kill();
+		}
+
+		private void Process_Exited(object sender, System.EventArgs e)
+		{
+			Terminated?.Invoke(process.ExitCode);
 		}
 	}
 }