Feature: Added a notification when the app goes to the background for the first time (#14673)

Co-authored-by: Yair <39923744+yaira2@users.noreply.github.com>

Author: hishitetsu

src/Files.App/App.xaml.cs

@@ -2,13 +2,15 @@
 // Licensed under the MIT License. See the LICENSE.
 
 using CommunityToolkit.WinUI.Helpers;
+using CommunityToolkit.WinUI.Notifications;
 using Microsoft.Extensions.Logging;
 using Microsoft.UI.Xaml;
 using Microsoft.UI.Xaml.Controls;
 using Microsoft.Windows.AppLifecycle;
 using Windows.ApplicationModel;
 using Windows.ApplicationModel.DataTransfer;
 using Windows.Storage;
+using Windows.UI.Notifications;
 
 namespace Files.App
 {
@@ -234,6 +236,40 @@ private async void Window_Closed(object sender, WindowEventArgs args)
 
 				Thread.Yield();
 
+				// Displays a notification the first time the app goes to the background
+				if (userSettingsService.AppSettingsService.ShowBackgroundRunningNotification)
+				{
+					userSettingsService.AppSettingsService.ShowBackgroundRunningNotification = false;
+
+					var toastContent = new ToastContent()
+					{
+						Visual = new()
+						{
+							BindingGeneric = new ToastBindingGeneric()
+							{
+								Children =
+								{
+									new AdaptiveText()
+									{
+										Text = "BackgroundRunningNotificationHeader".GetLocalizedResource()
+									},
+									new AdaptiveText()
+									{
+										Text = "BackgroundRunningNotificationBody".GetLocalizedResource()
+									}
+								},
+							}
+						},
+						ActivationType = ToastActivationType.Protocol
+					};
+
+					// Create the toast notification
+					var toastNotification = new ToastNotification(toastContent.GetXml());
+
+					// And send the notification
+					ToastNotificationManager.CreateToastNotifier().Show(toastNotification);
+				}
+
 				if (Program.Pool.WaitOne())
 				{
 					// Resume the instance

src/Files.App/Services/Settings/AppSettingsService.cs

@@ -21,6 +21,12 @@ public bool ShowStatusCenterTeachingTip
 			set => Set(value);
 		}
 
+		public bool ShowBackgroundRunningNotification
+		{
+			get => Get(true);
+			set => Set(value);
+		}
+
 		public bool RestoreTabsOnStartup
 		{
 			get => Get(false);

src/Files.App/Strings/en-US/Resources.resw

@@ -3685,4 +3685,10 @@
   <data name="ChangeAlbumCover" xml:space="preserve">
     <value>Change album cover</value>
   </data>
+  <data name="BackgroundRunningNotificationBody" xml:space="preserve">
+    <value>Files is still running in the background to improve startup performance.</value>
+  </data>
+  <data name="BackgroundRunningNotificationHeader" xml:space="preserve">
+    <value>Where did Files go?</value>
+  </data>
 </root>

src/Files.Core/Services/Settings/IAppSettingsService.cs

@@ -10,6 +10,11 @@ public interface IAppSettingsService : IBaseSettingsService, INotifyPropertyChan
 		/// </summary>
 		bool ShowStatusCenterTeachingTip { get; set; }
 
+		/// <summary>
+		/// Gets or sets a value indicating whether or not to show the notification to inform background running.
+		/// </summary>
+		bool ShowBackgroundRunningNotification { get; set; }
+
 		/// <summary>
 		/// Gets or sets a value indicating whether or not to restore tabs on startup.
 		/// This is used when prompting users to restart after changing the app language.