Moved sleep mode prevention to separate method of IDisplayMonitor.

SafeExamBrowser.Contracts/Monitoring/IDisplayMonitor.cs

@@ -18,11 +18,15 @@ namespace SafeExamBrowser.Contracts.Monitoring
 		event DisplayChangedEventHandler DisplayChanged;
 		
 		/// <summary>
-		/// Sets the desktop working area to accommodate to the taskbar's height, removes the configured wallpaper (if possible) and
+		/// Sets the desktop working area to accommodate to the taskbar's height and removes the configured wallpaper (if possible).
-		/// prevents the computer from entering sleep mode or turning its display(s) off.
 		/// </summary>
 		void InitializePrimaryDisplay(int taskbarHeight);
 
+		/// <summary>
+		/// Prevents the computer from entering sleep mode and turning its display(s) off.
+		/// </summary>
+		void PreventSleepMode();
+
 		/// <summary>
 		/// Resets the desktop working area and wallpaper to their previous (initial) state.
 		/// </summary>

SafeExamBrowser.Contracts/WindowsApi/INativeMethods.cs

@@ -38,11 +38,6 @@ namespace SafeExamBrowser.Contracts.WindowsApi
 		/// </exception>
 		void DeregisterSystemEvent(IntPtr handle);
 
-		/// <summary>
-		/// Prevents Windows from entering sleep mode and keeps all displays powered on.
-		/// </summary>
-		void DisableSleep();
-
 		/// <summary>
 		/// Empties the clipboard.
 		/// </summary>
@@ -115,6 +110,11 @@ namespace SafeExamBrowser.Contracts.WindowsApi
 		/// </exception>
 		void PostCloseMessageToShell();
 
+		/// <summary>
+		/// Prevents Windows from entering sleep mode and keeps all displays powered on.
+		/// </summary>
+		void PreventSleepMode();
+
 		/// <summary>
 		/// Registers a system hook for the given keyboard interceptor.
 		/// </summary>

SafeExamBrowser.Core/Behaviour/Operations/DisplayMonitorOperation.cs

@@ -34,6 +34,7 @@ namespace SafeExamBrowser.Core.Behaviour.Operations
 			logger.Info("Initializing working area...");
 			SplashScreen.UpdateText(TextKey.SplashScreen_InitializeWorkingArea);
 
+			displayMonitor.PreventSleepMode();
 			displayMonitor.InitializePrimaryDisplay(taskbar.GetAbsoluteHeight());
 			displayMonitor.StartMonitoringDisplayChanges();
 		}

SafeExamBrowser.Monitoring/Display/DisplayMonitor.cs

@@ -34,7 +34,12 @@ namespace SafeExamBrowser.Monitoring.Display
 		{
 			InitializeWorkingArea(taskbarHeight);
 			InitializeWallpaper();
-			PreventSleepMode();
+		}
+
+		public void PreventSleepMode()
+		{
+			nativeMethods.PreventSleepMode();
+			logger.Info("Disabled sleep mode and display timeout.");
 		}
 
 		public void ResetPrimaryDisplay()
@@ -94,12 +99,6 @@ namespace SafeExamBrowser.Monitoring.Display
 			}
 		}
 
-		private void PreventSleepMode()
-		{
-			nativeMethods.DisableSleep();
-			logger.Info("Disabled sleep mode and display timeout.");
-		}
-
 		private void ResetWorkingArea()
 		{
 			var identifier = GetIdentifierForPrimaryDisplay();

SafeExamBrowser.UserInterface/Taskbar.xaml.cs

@@ -50,7 +50,7 @@ namespace SafeExamBrowser.UserInterface
 			{
 				var height = (int) TransformToPhysical(Width, Height).Y;
 
-				logger.Info($"Calculated absolute taskbar height is {height}px.");
+				logger.Info($"Calculated physical taskbar height is {height}px.");
 
 				return height;
 			});

SafeExamBrowser.WindowsApi/NativeMethods.cs

@@ -94,11 +94,6 @@ namespace SafeExamBrowser.WindowsApi
 			EventDelegates.TryRemove(handle, out EventProc d);
 		}
 
-		public void DisableSleep()
-		{
-			Kernel32.SetThreadExecutionState(EXECUTION_STATE.CONTINUOUS | EXECUTION_STATE.DISPLAY_REQUIRED | EXECUTION_STATE.SYSTEM_REQUIRED);
-		}
-
 		public void EmptyClipboard()
 		{
 			var success = true;
@@ -225,6 +220,11 @@ namespace SafeExamBrowser.WindowsApi
 			}
 		}
 
+		public void PreventSleepMode()
+		{
+			Kernel32.SetThreadExecutionState(EXECUTION_STATE.CONTINUOUS | EXECUTION_STATE.DISPLAY_REQUIRED | EXECUTION_STATE.SYSTEM_REQUIRED);
+		}
+
 		public void RegisterKeyboardHook(IKeyboardInterceptor interceptor)
 		{
 			var hook = new KeyboardHook(interceptor);