Refactor: Close all dialogs asynchronously

Author: seer-by-sentry[bot]

src/Files.App/App.xaml.cs

@@ -234,7 +234,7 @@ private async void Window_Closed(object sender, WindowEventArgs args)
 				!Process.GetProcessesByName("Files").Any(x => x.Id != Environment.ProcessId))
 			{
 				// Close open content dialogs
-				UIHelpers.CloseAllDialogs();
+				await UIHelpers.CloseAllDialogsAsync();
 
 				// Close all notification banners except in progress
 				statusCenterViewModel.RemoveAllCompletedItems();

src/Files.App/Helpers/UI/UIHelpers.cs

@@ -102,6 +102,26 @@ public static void CloseAllDialogs()
 					dialog.Hide();
 		}
 
+		public static async Task CloseAllDialogsAsync()
+		{
+			if (MainWindow.Instance?.Content?.XamlRoot == null)
+				return;
+
+			var openedDialogs = VisualTreeHelper.GetOpenPopupsForXamlRoot(MainWindow.Instance.Content.XamlRoot);
+			var closingTasks = new List<Task>();
+			foreach (var item in openedDialogs)
+			{
+				if (item.Child is ContentDialog dialog)
+				{
+					var tcs = new TaskCompletionSource();
+					dialog.Closed += (s, e) => tcs.SetResult();
+					dialog.Hide();
+					closingTasks.Add(tcs.Task);
+				}
+			}
+			await Task.WhenAll(closingTasks);
+		}
+
 		private static IEnumerable<IconFileInfo> SidebarIconResources = LoadSidebarIconResources();
 
 		private static IconFileInfo ShieldIconResource = LoadShieldIconResource();