Implemented basic clipboard operation and made loading of icons failsafe (i.e. a red "X" will be displayed if an icon cannot be loaded).

SafeExamBrowser.Contracts/I18n/TextKey.cs

@@ -23,6 +23,7 @@ namespace SafeExamBrowser.Contracts.I18n
 		MessageBox_StartupErrorTitle,
 		Notification_AboutTooltip,
 		Notification_LogTooltip,
+		SplashScreen_EmptyClipboard,
 		SplashScreen_InitializeBrowser,
 		SplashScreen_InitializeProcessMonitoring,
 		SplashScreen_InitializeTaskbar,

SafeExamBrowser.Contracts/WindowsApi/INativeMethods.cs

@@ -38,6 +38,14 @@ namespace SafeExamBrowser.Contracts.WindowsApi
 		/// </exception>
 		void DeregisterSystemEvent(IntPtr handle);
 
+		/// <summary>
+		/// Empties the clipboard.
+		/// </summary>
+		/// <exception cref="System.ComponentModel.Win32Exception">
+		/// If the emptying of the clipboard failed.
+		/// </exception>
+		void EmptyClipboard();
+
 		/// <summary>
 		/// Retrieves a collection of handles to all currently open (i.e. visible) windows.
 		/// </summary>

SafeExamBrowser.Core/Behaviour/Operations/ClipboardOperation.cs

@@ -0,0 +1,48 @@
+/*
+ * 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.UserInterface;
+using SafeExamBrowser.Contracts.WindowsApi;
+
+namespace SafeExamBrowser.Core.Behaviour.Operations
+{
+	public class ClipboardOperation : IOperation
+	{
+		private ILogger logger;
+		private INativeMethods nativeMethods;
+
+		public ISplashScreen SplashScreen { private get; set; }
+
+		public ClipboardOperation(ILogger logger, INativeMethods nativeMethods)
+		{
+			this.logger = logger;
+			this.nativeMethods = nativeMethods;
+		}
+
+		public void Perform()
+		{
+			EmptyClipboard();
+		}
+
+		public void Revert()
+		{
+			EmptyClipboard();
+		}
+
+		private void EmptyClipboard()
+		{
+			logger.Info("Emptying clipboard...");
+			SplashScreen.UpdateText(TextKey.SplashScreen_EmptyClipboard);
+
+			nativeMethods.EmptyClipboard();
+		}
+	}
+}

SafeExamBrowser.Core/I18n/Text.xml

@@ -8,6 +8,7 @@
   <MessageBox_StartupErrorTitle>Startup Error</MessageBox_StartupErrorTitle>
   <Notification_AboutTooltip>About Safe Exam Browser</Notification_AboutTooltip>
   <Notification_LogTooltip>Application Log</Notification_LogTooltip>
+  <SplashScreen_EmptyClipboard>Emptying clipboard</SplashScreen_EmptyClipboard>
   <SplashScreen_InitializeBrowser>Initializing browser</SplashScreen_InitializeBrowser>
   <SplashScreen_InitializeProcessMonitoring>Initializing process monitoring</SplashScreen_InitializeProcessMonitoring>
   <SplashScreen_InitializeTaskbar>Initializing taskbar</SplashScreen_InitializeTaskbar>

SafeExamBrowser.Core/SafeExamBrowser.Core.csproj

@@ -58,6 +58,7 @@
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="Behaviour\Operations\ClipboardOperation.cs" />
     <Compile Include="Behaviour\Operations\KeyboardInterceptorOperation.cs" />
     <Compile Include="Behaviour\Operations\MouseInterceptorOperation.cs" />
     <Compile Include="Behaviour\RuntimeController.cs" />

SafeExamBrowser.UserInterface/Utilities/IconResourceLoader.cs

@@ -9,7 +9,9 @@
 using System;
 using System.Windows;
 using System.Windows.Controls;
+using System.Windows.Documents;
 using System.Windows.Markup;
+using System.Windows.Media;
 using System.Windows.Media.Imaging;
 using SafeExamBrowser.Contracts.Configuration;
 
@@ -19,22 +21,39 @@ namespace SafeExamBrowser.UserInterface.Utilities
 	{
 		internal static UIElement Load(IIconResource resource)
 		{
-			if (resource.IsBitmapResource)
+			try
 			{
-				return new Image
+				if (resource.IsBitmapResource)
 				{
-					Source = new BitmapImage(resource.Uri)
+					return LoadBitmapResource(resource);
-				};
-			}
-			else if (resource.IsXamlResource)
-			{
-				using (var stream = Application.GetResourceStream(resource.Uri)?.Stream)
-				{
-					return XamlReader.Load(stream) as UIElement;
 				}
+				else if (resource.IsXamlResource)
+				{
+					return LoadXamlResource(resource);
+				}
+			}
+			catch (Exception)
+			{
+				return new TextBlock(new Run("X") { Foreground = Brushes.Red, FontWeight = FontWeights.Bold });
 			}
 
 			throw new NotSupportedException($"Application icon resource of type '{resource.GetType()}' is not supported!");
 		}
+
+		private static UIElement LoadBitmapResource(IIconResource resource)
+		{
+			return new Image
+			{
+				Source = new BitmapImage(resource.Uri)
+			};
+		}
+
+		private static UIElement LoadXamlResource(IIconResource resource)
+		{
+			using (var stream = Application.GetResourceStream(resource.Uri)?.Stream)
+			{
+				return XamlReader.Load(stream) as UIElement;
+			}
+		}
 	}
 }

SafeExamBrowser.WindowsApi/NativeMethods.cs

@@ -94,6 +94,20 @@ namespace SafeExamBrowser.WindowsApi
 			EventDelegates.TryRemove(handle, out EventProc d);
 		}
 
+		public void EmptyClipboard()
+		{
+			var success = true;
+
+			success &= User32.OpenClipboard(IntPtr.Zero);
+			success &= User32.EmptyClipboard();
+			success &= User32.CloseClipboard();
+
+			if (!success)
+			{
+				throw new Win32Exception(Marshal.GetLastWin32Error());
+			}
+		}
+
 		public IEnumerable<IntPtr> GetOpenWindows()
 		{
 			var windows = new List<IntPtr>();

SafeExamBrowser.WindowsApi/User32.cs

@@ -26,6 +26,14 @@ namespace SafeExamBrowser.WindowsApi
 		[DllImport("user32.dll", SetLastError = true)]
 		internal static extern IntPtr CallNextHookEx(IntPtr hhk, int nCode, IntPtr wParam, IntPtr lParam);
 
+		[DllImport("user32.dll", SetLastError = true)]
+		[return: MarshalAs(UnmanagedType.Bool)]
+		internal static extern bool CloseClipboard();
+
+		[DllImport("user32.dll", SetLastError = true)]
+		[return: MarshalAs(UnmanagedType.Bool)]
+		internal static extern bool EmptyClipboard();
+
 		[DllImport("user32.dll", SetLastError = true)]
 		[return: MarshalAs(UnmanagedType.Bool)]
 		internal static extern bool EnumWindows(EnumWindowsDelegate enumProc, IntPtr lParam);
@@ -46,6 +54,10 @@ namespace SafeExamBrowser.WindowsApi
 		[return: MarshalAs(UnmanagedType.Bool)]
 		internal static extern bool IsWindowVisible(IntPtr hWnd);
 
+		[DllImport("user32.dll", SetLastError = true)]
+		[return: MarshalAs(UnmanagedType.Bool)]
+		internal static extern bool OpenClipboard(IntPtr hWndNewOwner);
+
 		[DllImport("user32.dll", SetLastError = true)]
 		[return: MarshalAs(UnmanagedType.Bool)]
 		internal static extern bool PostMessage(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam);

SafeExamBrowser/CompositionRoot.cs

@@ -86,6 +86,7 @@ namespace SafeExamBrowser
 			StartupOperations.Enqueue(new TaskbarOperation(logger, logFormatter, settings, Taskbar, text, uiFactory));
 			StartupOperations.Enqueue(new BrowserOperation(browserController, browserInfo, logger, Taskbar, uiFactory));
 			StartupOperations.Enqueue(new RuntimeControllerOperation(runtimeController, logger));
+			StartupOperations.Enqueue(new ClipboardOperation(logger, nativeMethods));
 			StartupOperations.Enqueue(new MouseInterceptorOperation(logger, mouseInterceptor, nativeMethods));
 		}
 	}