Fix: Switch focus to Files when activating window (#13588)

Author: yaira2

src/Files.App/Helpers/Interop/InteropHelpers.cs

@@ -28,6 +28,9 @@ public static class InteropHelpers
 		[DllImport("kernel32.dll")]
 		public static extern bool SetEvent(IntPtr hEvent);
 
+		[DllImport("user32.dll", SetLastError = true)]
+		public static extern void SwitchToThisWindow(IntPtr hWnd, bool altTab);
+
 		[DllImport("ole32.dll")]
 		public static extern uint CoWaitForMultipleObjects(uint dwFlags, uint dwMilliseconds, ulong nHandles, IntPtr[] pHandles, out uint dwIndex);
 

src/Files.App/MainWindow.xaml.cs

@@ -97,6 +97,7 @@ public async Task InitializeApplicationAsync(object activatedEventArgs)
 					}
 					else if (!(string.IsNullOrEmpty(launchArgs.Arguments) && MainPageViewModel.AppInstances.Count > 0))
 					{
+						InteropHelpers.SwitchToThisWindow(WindowHandle, true);
 						await mainPageViewModel.AddNewTabByPathAsync(typeof(PaneHolderPage), launchArgs.Arguments);
 					}
 					else
@@ -173,6 +174,8 @@ public async Task InitializeApplicationAsync(object activatedEventArgs)
 						rootFrame.Navigate(typeof(MainPage), fileArgs.Files.First().Path, new SuppressNavigationTransitionInfo());
 						index = 1;
 					}
+					else
+						InteropHelpers.SwitchToThisWindow(WindowHandle, true);
 					for (; index < fileArgs.Files.Count; index++)
 					{
 						await mainPageViewModel.AddNewTabByPathAsync(typeof(PaneHolderPage), fileArgs.Files[index].Path);
@@ -235,7 +238,10 @@ async Task PerformNavigationAsync(string payload, string selectItem = null)
 				};
 
 				if (rootFrame.Content is MainPage && MainPageViewModel.AppInstances.Any())
+				{
+					InteropHelpers.SwitchToThisWindow(WindowHandle, true);
 					await mainPageViewModel.AddNewTabByParamAsync(typeof(PaneHolderPage), paneNavigationArgs);
+				}
 				else
 					rootFrame.Navigate(typeof(MainPage), paneNavigationArgs, new SuppressNavigationTransitionInfo());
 			}