Enhanced startup- and shutdown-procedure by introducing a stack of IOperations (which are automatically reverted on shutdown or if an error happens during startup).

SafeExamBrowser.Configuration/WorkingArea.cs

@@ -18,7 +18,7 @@ namespace SafeExamBrowser.Configuration
 	public class WorkingArea : IWorkingArea
 	{
 		private ILogger logger;
-		private RECT? initial;
+		private RECT? originalWorkingArea;
 
 		public WorkingArea(ILogger logger)
 		{
@@ -27,9 +27,9 @@ namespace SafeExamBrowser.Configuration
 
 		public void InitializeFor(ITaskbar taskbar)
 		{
-			initial = User32.GetWorkingArea();
+			originalWorkingArea = User32.GetWorkingArea();
 
-			LogWorkingArea("Saved initial working area", initial.Value);
+			LogWorkingArea("Saved original working area", originalWorkingArea.Value);
 
 			var area = new RECT
 			{
@@ -39,17 +39,17 @@ namespace SafeExamBrowser.Configuration
 				Bottom = Screen.PrimaryScreen.Bounds.Height - taskbar.GetAbsoluteHeight()
 			};
 
-			LogWorkingArea("Setting new working area", area);
+			LogWorkingArea("Trying to set new working area", area);
 			User32.SetWorkingArea(area);
 			LogWorkingArea("Working area is now set to", User32.GetWorkingArea());
 		}
 
 		public void Reset()
 		{
-			if (initial.HasValue)
+			if (originalWorkingArea.HasValue)
 			{
-				User32.SetWorkingArea(initial.Value);
+				User32.SetWorkingArea(originalWorkingArea.Value);
-				LogWorkingArea("Restored initial working area", initial.Value);
+				LogWorkingArea("Restored original working area", originalWorkingArea.Value);
 			}
 		}
 

SafeExamBrowser.Contracts/Behaviour/IOperation.cs

@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2017 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 SafeExamBrowser.Contracts.UserInterface;
+
+namespace SafeExamBrowser.Contracts.Behaviour
+{
+	public interface IOperation
+	{
+		/// <summary>
+		/// The splash screen to be used to show status information to the user.
+		/// </summary>
+		ISplashScreen SplashScreen { set; }
+
+		/// <summary>
+		/// Performs the operation.
+		/// </summary>
+		void Perform();
+
+		/// <summary>
+		/// Reverts all changes which were made when performing the operation.
+		/// </summary>
+		void Revert();
+	}
+}

SafeExamBrowser.Contracts/Behaviour/IShutdownController.cs

@@ -6,6 +6,8 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
+using System.Collections.Generic;
+
 namespace SafeExamBrowser.Contracts.Behaviour
 {
 	public interface IShutdownController
@@ -13,6 +15,6 @@ namespace SafeExamBrowser.Contracts.Behaviour
 		/// <summary>
 		/// Reverts any changes performed during the startup or runtime and releases all used resources.
 		/// </summary>
-		void FinalizeApplication();
+		void FinalizeApplication(Stack<IOperation> operations);
 	}
 }

SafeExamBrowser.Contracts/Behaviour/IStartupController.cs

@@ -6,14 +6,17 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
+using System.Collections.Generic;
+
 namespace SafeExamBrowser.Contracts.Behaviour
 {
 	public interface IStartupController
 	{
 		/// <summary>
 		/// Tries to initialize the application. Returns <c>true</c> if the initialization was successful,
-		/// <c>false</c> otherwise.
+		/// <c>false</c> otherwise. All operations performed during the startup procedure will be registered
+		/// to the given <c>out</c> parameter.
 		/// </summary>
-		bool TryInitializeApplication();
+		bool TryInitializeApplication(out Stack<IOperation> operations);
 	}
 }

SafeExamBrowser.Contracts/SafeExamBrowser.Contracts.csproj

@@ -42,6 +42,7 @@
   <ItemGroup>
     <Compile Include="Behaviour\IApplicationController.cs" />
     <Compile Include="Behaviour\INotificationController.cs" />
+    <Compile Include="Behaviour\IOperation.cs" />
     <Compile Include="Configuration\IIconResource.cs" />
     <Compile Include="Configuration\IApplicationInfo.cs" />
     <Compile Include="Configuration\IApplicationInstance.cs" />

SafeExamBrowser.Contracts/UserInterface/ISplashScreen.cs

@@ -22,16 +22,27 @@ namespace SafeExamBrowser.Contracts.UserInterface
 		/// </summary>
 		void InvokeShow();
 
+		/// <summary>
+		/// Updates the progress bar of the splash screen according to the specified amount.
+		/// </summary>
+		void Progress(int amount = 1);
+
+		/// <summary>
+		/// Regresses the progress bar of the splash screen according to the specified amount.
+		/// </summary>
+		void Regress(int amount = 1);
+
+		/// <summary>
+		/// Sets the style of the progress bar to indeterminate, i.e. <c>Progress</c> and
+		/// <c>Regress</c> won't have any effect when called.
+		/// </summary>
+		void SetIndeterminate();
+
 		/// <summary>
 		/// Set the maximum of the splash screen's progress bar.
 		/// </summary>
 		void SetMaxProgress(int max);
 
-		/// <summary>
-		/// Updates the progress bar of the splash screen according to the specified amount.
-		/// </summary>
-		void UpdateProgress(int amount = 1);
-
 		/// <summary>
 		/// Updates the status text of the splash screen. If the busy flag is set,
 		/// the splash screen will show an animation to indicate a long-running operation.

SafeExamBrowser.Core/Behaviour/Operations/BrowserInitializationOperation.cs

@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2017 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 SafeExamBrowser.Contracts.Behaviour;
+using SafeExamBrowser.Contracts.Configuration;
+using SafeExamBrowser.Contracts.I18n;
+using SafeExamBrowser.Contracts.Logging;
+using SafeExamBrowser.Contracts.UserInterface;
+
+namespace SafeExamBrowser.Core.Behaviour.Operations
+{
+	class BrowserInitializationOperation : IOperation
+	{
+		private IApplicationController browserController;
+		private IApplicationInfo browserInfo;
+		private ILogger logger;
+		private ITaskbar taskbar;
+		private IUiElementFactory uiFactory;
+
+		public ISplashScreen SplashScreen { private get; set; }
+
+		public BrowserInitializationOperation(
+			IApplicationController browserController,
+			IApplicationInfo browserInfo,
+			ILogger logger,
+			ITaskbar taskbar,
+			IUiElementFactory uiFactory)
+		{
+			this.browserController = browserController;
+			this.browserInfo = browserInfo;
+			this.logger = logger;
+			this.taskbar = taskbar;
+			this.uiFactory = uiFactory;
+		}
+
+		public void Perform()
+		{
+			logger.Info("--- Initializing browser ---");
+			SplashScreen.UpdateText(Key.SplashScreen_InitializeBrowser);
+
+			var browserButton = uiFactory.CreateApplicationButton(browserInfo);
+
+			browserController.RegisterApplicationButton(browserButton);
+			taskbar.AddButton(browserButton);
+		}
+
+		public void Revert()
+		{
+			// Nothing to do here so far...
+		}
+	}
+}

SafeExamBrowser.Core/Behaviour/Operations/ProcessMonitoringOperation.cs

@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2017 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 SafeExamBrowser.Contracts.Behaviour;
+using SafeExamBrowser.Contracts.I18n;
+using SafeExamBrowser.Contracts.Logging;
+using SafeExamBrowser.Contracts.Monitoring;
+using SafeExamBrowser.Contracts.UserInterface;
+
+namespace SafeExamBrowser.Core.Behaviour.Operations
+{
+	class ProcessMonitoringOperation : IOperation
+	{
+		private ILogger logger;
+		private IProcessMonitor processMonitor;
+
+		public ISplashScreen SplashScreen { private get; set; }
+
+		public ProcessMonitoringOperation(ILogger logger, IProcessMonitor processMonitor)
+		{
+			this.logger = logger;
+			this.processMonitor = processMonitor;
+		}
+
+		public void Perform()
+		{
+			logger.Info("--- Initializing process monitoring ---");
+			SplashScreen.UpdateText(Key.SplashScreen_InitializeProcessMonitoring);
+
+			// TODO
+		}
+
+		public void Revert()
+		{
+			logger.Info("--- Stopping process monitoring ---");
+			SplashScreen.UpdateText(Key.SplashScreen_StopProcessMonitoring);
+
+			// TODO
+		}
+	}
+}

SafeExamBrowser.Core/Behaviour/Operations/TaskbarInitializationOperation.cs

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2017 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 SafeExamBrowser.Contracts.Behaviour;
+using SafeExamBrowser.Contracts.Configuration;
+using SafeExamBrowser.Contracts.I18n;
+using SafeExamBrowser.Contracts.Logging;
+using SafeExamBrowser.Contracts.UserInterface;
+
+namespace SafeExamBrowser.Core.Behaviour.Operations
+{
+	class TaskbarInitializationOperation : IOperation
+	{
+		private ILogger logger;
+		private ITaskbar taskbar;
+		private IUiElementFactory uiFactory;
+		private INotificationInfo aboutInfo;
+
+		public ISplashScreen SplashScreen { private get; set; }
+
+		public TaskbarInitializationOperation(ILogger logger, INotificationInfo aboutInfo, ITaskbar taskbar, IUiElementFactory uiFactory)
+		{
+			this.logger = logger;
+			this.aboutInfo = aboutInfo;
+			this.taskbar = taskbar;
+			this.uiFactory = uiFactory;
+		}
+
+		public void Perform()
+		{
+			logger.Info("--- Initializing taskbar ---");
+			SplashScreen.UpdateText(Key.SplashScreen_InitializeTaskbar);
+
+			var aboutNotification = uiFactory.CreateNotification(aboutInfo);
+
+			taskbar.AddNotification(aboutNotification);
+		}
+
+		public void Revert()
+		{
+			// Nothing to do here so far...
+		}
+	}
+}

SafeExamBrowser.Core/Behaviour/Operations/WorkingAreaOperation.cs

@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2017 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 SafeExamBrowser.Contracts.Behaviour;
+using SafeExamBrowser.Contracts.Configuration;
+using SafeExamBrowser.Contracts.I18n;
+using SafeExamBrowser.Contracts.Logging;
+using SafeExamBrowser.Contracts.Monitoring;
+using SafeExamBrowser.Contracts.UserInterface;
+
+namespace SafeExamBrowser.Core.Behaviour.Operations
+{
+	class WorkingAreaOperation : IOperation
+	{
+		private ILogger logger;
+		private IProcessMonitor processMonitor;
+		private ITaskbar taskbar;
+		private IWorkingArea workingArea;
+
+		public ISplashScreen SplashScreen { private get; set; }
+
+		public WorkingAreaOperation(ILogger logger, IProcessMonitor processMonitor, ITaskbar taskbar, IWorkingArea workingArea)
+		{
+			this.logger = logger;
+			this.processMonitor = processMonitor;
+			this.taskbar = taskbar;
+			this.workingArea = workingArea;
+		}
+
+		public void Perform()
+		{
+			logger.Info("--- Initializing working area ---");
+			SplashScreen.UpdateText(Key.SplashScreen_WaitExplorerTermination, true);
+
+			processMonitor.CloseExplorerShell();
+			processMonitor.StartMonitoringExplorer();
+
+			// TODO
+			// - Minimizing all open windows
+			// - Emptying clipboard
+
+			SplashScreen.UpdateText(Key.SplashScreen_InitializeWorkingArea);
+			workingArea.InitializeFor(taskbar);
+		}
+
+		public void Revert()
+		{
+			logger.Info("--- Restoring working area ---");
+			SplashScreen.UpdateText(Key.SplashScreen_RestoreWorkingArea);
+
+			// TODO
+			// - Restore all windows?
+			// - Emptying clipboard
+
+			workingArea.Reset();
+
+			SplashScreen.UpdateText(Key.SplashScreen_WaitExplorerStartup, true);
+
+			processMonitor.StopMonitoringExplorer();
+			processMonitor.StartExplorerShell();
+		}
+	}
+}

SafeExamBrowser.Core/Behaviour/ShutdownController.cs

@@ -30,16 +30,6 @@ namespace SafeExamBrowser.Core.Behaviour
 		private IUiElementFactory uiFactory;
 		private IWorkingArea workingArea;
 
-		private IEnumerable<Action> ShutdownOperations
-		{
-			get
-			{
-				yield return StopProcessMonitoring;
-				yield return RestoreWorkingArea;
-				yield return FinalizeApplicationLog;
-			}
-		}
-
 		public ShutdownController(
 			ILogger logger,
 			IMessageBox messageBox,
@@ -58,64 +48,62 @@ namespace SafeExamBrowser.Core.Behaviour
 			this.workingArea = workingArea;
 		}
 
-		public void FinalizeApplication()
+		public void FinalizeApplication(Stack<IOperation> operations)
 		{
 			try
 			{
 				InitializeSplashScreen();
-
+				RevertOperations(operations);
-				foreach (var operation in ShutdownOperations)
+				FinalizeApplicationLog();
-				{
-					operation();
-					splashScreen.UpdateProgress();
-
-					// TODO: Remove!
-					Thread.Sleep(250);
-				}
 			}
 			catch (Exception e)
 			{
-				logger.Error($"Failed to finalize application!", e);
+				LogAndShowException(e);
-				messageBox.Show(text.Get(Key.MessageBox_ShutdownError), text.Get(Key.MessageBox_ShutdownErrorTitle), icon: MessageBoxIcon.Error);
+				FinalizeApplicationLog(false);
+			}
+		}
+
+		private void RevertOperations(Stack<IOperation> operations)
+		{
+			while (operations.Any())
+			{
+				var operation = operations.Pop();
+
+				operation.SplashScreen = splashScreen;
+				operation.Revert();
+
+				splashScreen.Progress();
+
+				// TODO: Remove!
+				Thread.Sleep(250);
 			}
 		}
 
 		private void InitializeSplashScreen()
 		{
 			splashScreen = uiFactory.CreateSplashScreen(settings, text);
-			splashScreen.SetMaxProgress(ShutdownOperations.Count());
+			splashScreen.SetIndeterminate();
 			splashScreen.UpdateText(Key.SplashScreen_ShutdownProcedure);
 			splashScreen.InvokeShow();
 			logger.Info("--- Initiating shutdown procedure ---");
 		}
 
-		private void StopProcessMonitoring()
+		private void LogAndShowException(Exception e)
 		{
-			logger.Info("--- Stopping process monitoring ---");
+			logger.Error($"Failed to finalize application!", e);
-			splashScreen.UpdateText(Key.SplashScreen_StopProcessMonitoring);
+			messageBox.Show(text.Get(Key.MessageBox_ShutdownError), text.Get(Key.MessageBox_ShutdownErrorTitle), icon: MessageBoxIcon.Error);
-
-			// TODO
-
-			processMonitor.StopMonitoringExplorer();
 		}
 
-		private void RestoreWorkingArea()
+		private void FinalizeApplicationLog(bool success = true)
 		{
-			logger.Info("--- Restoring working area ---");
+			if (success)
-			splashScreen.UpdateText(Key.SplashScreen_RestoreWorkingArea);
-
-			// TODO
-
-			workingArea.Reset();
-
-			splashScreen.UpdateText(Key.SplashScreen_WaitExplorerStartup, true);
-			processMonitor.StartExplorerShell();
-		}
-
-		private void FinalizeApplicationLog()
 			{
 				logger.Info("--- Application successfully finalized! ---");
+			}
+			else
+			{
 				logger.Log($"{Environment.NewLine}# Application terminated at {DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss.fff")}");
 			}
 		}
+	}
 }

SafeExamBrowser.Core/Behaviour/StartupController.cs

@@ -16,6 +16,7 @@ using SafeExamBrowser.Contracts.I18n;
 using SafeExamBrowser.Contracts.Logging;
 using SafeExamBrowser.Contracts.Monitoring;
 using SafeExamBrowser.Contracts.UserInterface;
+using SafeExamBrowser.Core.Behaviour.Operations;
 
 namespace SafeExamBrowser.Core.Behaviour
 {
@@ -34,21 +35,7 @@ namespace SafeExamBrowser.Core.Behaviour
 		private IUiElementFactory uiFactory;
 		private IWorkingArea workingArea;
 
-		private IEnumerable<Action> StartupOperations
+		private IEnumerable<IOperation> startupOperations;
-		{
-			get
-			{
-				yield return HandleCommandLineArguments;
-				yield return DetectOperatingSystem;
-				yield return EstablishWcfServiceConnection;
-				yield return DeactivateWindowsFeatures;
-				yield return InitializeProcessMonitoring;
-				yield return InitializeWorkingArea;
-				yield return InitializeTaskbar;
-				yield return InitializeBrowser;
-				yield return FinishInitialization;
-			}
-		}
 
 		public StartupController(
 			IApplicationController browserController,
@@ -76,33 +63,78 @@ namespace SafeExamBrowser.Core.Behaviour
 			this.workingArea = workingArea;
 		}
 
-		public bool TryInitializeApplication()
+		public bool TryInitializeApplication(out Stack<IOperation> operations)
 		{
+			operations = new Stack<IOperation>();
+
 			try
 			{
+				CreateStartupOperations();
+
 				InitializeApplicationLog();
 				InitializeSplashScreen();
 
-				foreach (var operation in StartupOperations)
+				operations = PerformOperations();
-				{
-					operation();
-					splashScreen.UpdateProgress();
 
-					// TODO: Remove!
+				FinishInitialization();
-					Thread.Sleep(250);
-				}
 
 				return true;
 			}
 			catch (Exception e)
 			{
-				logger.Error($"Failed to initialize application!", e);
+				LogAndShowException(e);
-				messageBox.Show(text.Get(Key.MessageBox_StartupError), text.Get(Key.MessageBox_StartupErrorTitle), icon: MessageBoxIcon.Error);
+				RevertOperations(operations);
+				FinishInitialization(false);
 
 				return false;
 			}
 		}
 
+		private Stack<IOperation> PerformOperations()
+		{
+			var operations = new Stack<IOperation>();
+
+			foreach (var operation in startupOperations)
+			{
+				operations.Push(operation);
+
+				operation.SplashScreen = splashScreen;
+				operation.Perform();
+
+				splashScreen.Progress();
+
+				// TODO: Remove!
+				Thread.Sleep(250);
+			}
+
+			return operations;
+		}
+
+		private void RevertOperations(Stack<IOperation> operations)
+		{
+			while (operations.Any())
+			{
+				var operation = operations.Pop();
+
+				operation.Revert();
+				splashScreen.Regress();
+
+				// TODO: Remove!
+				Thread.Sleep(250);
+			}
+		}
+
+		private void CreateStartupOperations()
+		{
+			startupOperations = new IOperation[]
+			{
+				new ProcessMonitoringOperation(logger, processMonitor),
+				new WorkingAreaOperation(logger, processMonitor, taskbar, workingArea),
+				new TaskbarInitializationOperation(logger, aboutInfo, taskbar, uiFactory),
+				new BrowserInitializationOperation(browserController, browserInfo, logger, taskbar, uiFactory)
+			};
+		}
+
 		private void InitializeApplicationLog()
 		{
 			var titleLine = $"/* {settings.ProgramTitle}, Version {settings.ProgramVersion}{Environment.NewLine}";
@@ -118,84 +150,29 @@ namespace SafeExamBrowser.Core.Behaviour
 		private void InitializeSplashScreen()
 		{
 			splashScreen = uiFactory.CreateSplashScreen(settings, text);
-			splashScreen.SetMaxProgress(StartupOperations.Count());
+			splashScreen.SetMaxProgress(startupOperations.Count());
 			splashScreen.UpdateText(Key.SplashScreen_StartupProcedure);
 			splashScreen.InvokeShow();
 		}
 
-		private void HandleCommandLineArguments()
+		private void LogAndShowException(Exception e)
 		{
-			// TODO
+			logger.Error($"Failed to initialize application!", e);
+			messageBox.Show(text.Get(Key.MessageBox_StartupError), text.Get(Key.MessageBox_StartupErrorTitle), icon: MessageBoxIcon.Error);
+			logger.Info("Reverting operations...");
 		}
 
-		private void DetectOperatingSystem()
+		private void FinishInitialization(bool success = true)
 		{
-			// TODO
+			if (success)
-		}
-
-		private void EstablishWcfServiceConnection()
-		{
-			// TODO
-		}
-
-		private void DeactivateWindowsFeatures()
-		{
-			// TODO
-		}
-
-		private void InitializeProcessMonitoring()
-		{
-			logger.Info("--- Initializing process monitoring ---");
-			splashScreen.UpdateText(Key.SplashScreen_InitializeProcessMonitoring);
-
-			// TODO
-
-			processMonitor.StartMonitoringExplorer();
-		}
-
-		private void InitializeWorkingArea()
-		{
-			logger.Info("--- Initializing working area ---");
-			splashScreen.UpdateText(Key.SplashScreen_WaitExplorerTermination, true);
-			processMonitor.CloseExplorerShell();
-
-			// TODO
-			// - Minimizing all open windows
-			// - Emptying clipboard
-
-			splashScreen.UpdateText(Key.SplashScreen_InitializeWorkingArea);
-			workingArea.InitializeFor(taskbar);
-		}
-
-		private void InitializeTaskbar()
-		{
-			logger.Info("--- Initializing taskbar ---");
-			splashScreen.UpdateText(Key.SplashScreen_InitializeTaskbar);
-
-			// TODO
-
-			var aboutNotification = uiFactory.CreateNotification(aboutInfo);
-
-			taskbar.AddNotification(aboutNotification);
-		}
-
-		private void InitializeBrowser()
-		{
-			logger.Info("--- Initializing browser ---");
-			splashScreen.UpdateText(Key.SplashScreen_InitializeBrowser);
-
-			// TODO
-
-			var browserButton = uiFactory.CreateApplicationButton(browserInfo);
-
-			browserController.RegisterApplicationButton(browserButton);
-			taskbar.AddButton(browserButton);
-		}
-
-		private void FinishInitialization()
 			{
 				logger.Info("--- Application successfully initialized! ---");
 				splashScreen.InvokeClose();
 			}
+			else
+			{
+				logger.Log($"{Environment.NewLine}# Application terminated at {DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss.fff")}");
+			}
+		}
 	}
 }

SafeExamBrowser.Core/SafeExamBrowser.Core.csproj

@@ -40,6 +40,10 @@
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="Behaviour\Operations\BrowserInitializationOperation.cs" />
+    <Compile Include="Behaviour\Operations\ProcessMonitoringOperation.cs" />
+    <Compile Include="Behaviour\Operations\TaskbarInitializationOperation.cs" />
+    <Compile Include="Behaviour\Operations\WorkingAreaOperation.cs" />
     <Compile Include="Behaviour\ShutdownController.cs" />
     <Compile Include="Behaviour\StartupController.cs" />
     <Compile Include="Logging\LogFileWriter.cs" />

SafeExamBrowser.UserInterface/SplashScreen.xaml

@@ -22,7 +22,7 @@
                 <Image Grid.Column="0" Grid.ColumnSpan="2" Source="pack://application:,,,/SafeExamBrowser.UserInterface;component/Images/SplashScreen.png" />
                 <TextBlock x:Name="InfoTextBlock" Grid.Column="1" Foreground="White" Margin="10,75,10,10" TextWrapping="Wrap" />
             </Grid>
-            <ProgressBar x:Name="ProgressBar" Grid.Row="1" Minimum="0" Maximum="{Binding Path=MaxProgress}" Value="{Binding Path=CurrentProgress}" Background="#00000000" BorderThickness="0" />
+            <ProgressBar x:Name="ProgressBar" Grid.Row="1" Minimum="0" Maximum="{Binding Path=MaxProgress}" Value="{Binding Path=CurrentProgress}" IsIndeterminate="{Binding Path=IsIndeterminate}" Background="#00000000" BorderThickness="0" />
             <TextBlock x:Name="StatusTextBlock" Grid.Row="1" Text="{Binding Path=Status}" FontSize="12" HorizontalAlignment="Center" VerticalAlignment="Center" Foreground="White" />
         </Grid>
     </Border>

SafeExamBrowser.UserInterface/SplashScreen.xaml.cs

@@ -40,16 +40,26 @@ namespace SafeExamBrowser.UserInterface
 			Dispatcher.Invoke(Show);
 		}
 
+		public void Progress(int amount = 1)
+		{
+			model.CurrentProgress += amount;
+		}
+
+		public void Regress(int amount = 1)
+		{
+			model.CurrentProgress -= amount;
+		}
+
+		public void SetIndeterminate()
+		{
+			model.IsIndeterminate = true;
+		}
+
 		public void SetMaxProgress(int max)
 		{
 			model.MaxProgress = max;
 		}
 
-		public void UpdateProgress(int amount = 1)
-		{
-			model.CurrentProgress += amount;
-		}
-
 		public void UpdateText(Key key, bool showBusyIndication = false)
 		{
 			model.StopBusyIndication();

SafeExamBrowser.UserInterface/Taskbar.xaml

@@ -6,7 +6,7 @@
         xmlns:local="clr-namespace:SafeExamBrowser.UserInterface.Controls"
         xmlns:s="clr-namespace:System;assembly=mscorlib"
         mc:Ignorable="d"
-        Title="Taskbar" Height="40" Width="750" WindowStyle="None" AllowsTransparency="True" Topmost="True" Icon="./Images/SafeExamBrowser.ico">
+        Title="Taskbar" Height="40" Width="750" WindowStyle="None" AllowsTransparency="True" Topmost="True" Visibility="Collapsed" Icon="./Images/SafeExamBrowser.ico">
     <Window.Background>
         <SolidColorBrush Color="Black" Opacity="0.8" />
     </Window.Background>

SafeExamBrowser.UserInterface/ViewModels/SplashScreenViewModel.cs

@@ -14,6 +14,7 @@ namespace SafeExamBrowser.UserInterface.ViewModels
 	class SplashScreenViewModel : INotifyPropertyChanged
 	{
 		private int currentProgress;
+		private bool isIndeterminate;
 		private int maxProgress;
 		private string status;
 		private Timer busyTimer;
@@ -33,6 +34,19 @@ namespace SafeExamBrowser.UserInterface.ViewModels
 			}
 		}
 
+		public bool IsIndeterminate
+		{
+			get
+			{
+				return isIndeterminate;
+			}
+			set
+			{
+				isIndeterminate = value;
+				PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(IsIndeterminate)));
+			}
+		}
+
 		public int MaxProgress
 		{
 			get

SafeExamBrowser/App.cs

@@ -7,8 +7,10 @@
  */
 
 using System;
+using System.Collections.Generic;
 using System.Threading;
 using System.Windows;
+using SafeExamBrowser.Contracts.Behaviour;
 
 namespace SafeExamBrowser
 {
@@ -57,12 +59,12 @@ namespace SafeExamBrowser
 
 			instances.BuildObjectGraph();
 
-			var success = instances.StartupController.TryInitializeApplication();
+			var success = instances.StartupController.TryInitializeApplication(out Stack<IOperation> operations);
 
 			if (success)
 			{
 				MainWindow = instances.Taskbar;
-				MainWindow.Closing += (o, args) => ShutdownApplication();
+				MainWindow.Closing += (o, args) => ShutdownApplication(operations);
 				MainWindow.Show();
 			}
 			else
@@ -71,10 +73,10 @@ namespace SafeExamBrowser
 			}
 		}
 
-		private void ShutdownApplication()
+		private void ShutdownApplication(Stack<IOperation> operations)
 		{
 			MainWindow.Hide();
-			instances.ShutdownController.FinalizeApplication();
+			instances.ShutdownController.FinalizeApplication(operations);
 		}
 	}
 }