Revert "Removes workaround theming code for WinUI 3 custom titlebar" => solving title bar problem when changing theme (#4638)

Reverts back removal of titlebar workaround because it was causing bugs for some users in Windows 10.

code/TemplateStudioForWinUICs/TemplateStudioForWinUICs.csproj

@@ -265,6 +265,9 @@
     <Content Include="Templates\Ft\AppNotifications\Param_ProjectName\Services\AppNotificationService.cs">
       <IncludeInVSIX>true</IncludeInVSIX>
     </Content>
+    <Content Include="Templates\Proj\Default\Param_ProjectName\Helpers\TitleBarHelper.cs">
+      <IncludeInVSIX>true</IncludeInVSIX>
+    </Content>
     <Content Include="Templates\_comp\MT\Project.MenuBar.AddMenuItem.Settings\Views\ShellPage_postaction.xaml.cs">
       <IncludeInVSIX>true</IncludeInVSIX>
     </Content>

code/TemplateStudioForWinUICs/Templates/Ft/ThemeSelection/Services/ThemeSelectorService.cs

@@ -37,6 +37,8 @@ public class ThemeSelectorService : IThemeSelectorService
         if (App.MainWindow.Content is FrameworkElement rootElement)
         {
             rootElement.RequestedTheme = Theme;
+
+            TitleBarHelper.UpdateTitleBar(Theme);
         }
 
         await Task.CompletedTask;

code/TemplateStudioForWinUICs/Templates/Proj/Default/Param_ProjectName/App.xaml

@@ -10,8 +10,6 @@
                 <ResourceDictionary Source="/Styles/Thickness.xaml" />
                 <ResourceDictionary Source="/Styles/TextBlock.xaml" />
             </ResourceDictionary.MergedDictionaries>
-            <SolidColorBrush x:Key="WindowCaptionBackground">Transparent</SolidColorBrush>
-            <SolidColorBrush x:Key="WindowCaptionBackgroundDisabled">Transparent</SolidColorBrush>
         </ResourceDictionary>
     </Application.Resources>
 </Application>

code/TemplateStudioForWinUICs/Templates/Proj/Default/Param_ProjectName/Helpers/TitleBarHelper.cs

@@ -0,0 +1,100 @@
+using System.Runtime.InteropServices;
+using Microsoft.UI;
+using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Media;
+using Windows.UI;
+using Windows.UI.ViewManagement;
+
+namespace Param_RootNamespace.Helpers;
+
+// Helper class to workaround custom title bar bugs.
+// DISCLAIMER: The resource key names and color values used below are subject to change. Do not depend on them.
+// https://github.com/microsoft/TemplateStudio/issues/4516
+internal class TitleBarHelper
+{
+    private const int WAINACTIVE = 0x00;
+    private const int WAACTIVE = 0x01;
+    private const int WMACTIVATE = 0x0006;
+
+    [DllImport("user32.dll")]
+    private static extern IntPtr GetActiveWindow();
+
+    [DllImport("user32.dll", CharSet = CharSet.Auto)]
+    private static extern IntPtr SendMessage(IntPtr hWnd, int msg, int wParam, IntPtr lParam);
+
+    public static void UpdateTitleBar(ElementTheme theme)
+    {
+        if (App.MainWindow.ExtendsContentIntoTitleBar)
+        {
+            if (theme == ElementTheme.Default)
+            {
+                var uiSettings = new UISettings();
+                var background = uiSettings.GetColorValue(UIColorType.Background);
+
+                theme = background == Colors.White ? ElementTheme.Light : ElementTheme.Dark;
+            }
+            
+            if (theme == ElementTheme.Default)
+            {
+                theme = Application.Current.RequestedTheme == ApplicationTheme.Light ? ElementTheme.Light : ElementTheme.Dark;
+            }
+
+            Application.Current.Resources["WindowCaptionForeground"] = theme switch
+            {
+                ElementTheme.Dark => new SolidColorBrush(Colors.White),
+                ElementTheme.Light => new SolidColorBrush(Colors.Black),
+                _ => new SolidColorBrush(Colors.Transparent)
+            };
+
+            Application.Current.Resources["WindowCaptionForegroundDisabled"] = theme switch
+            {
+                ElementTheme.Dark => new SolidColorBrush(Color.FromArgb(0x66, 0xFF, 0xFF, 0xFF)),
+                ElementTheme.Light => new SolidColorBrush(Color.FromArgb(0x66, 0x00, 0x00, 0x00)),
+                _ => new SolidColorBrush(Colors.Transparent)
+            };
+
+            Application.Current.Resources["WindowCaptionButtonBackgroundPointerOver"] = theme switch
+            {
+                ElementTheme.Dark => new SolidColorBrush(Color.FromArgb(0x33, 0xFF, 0xFF, 0xFF)),
+                ElementTheme.Light => new SolidColorBrush(Color.FromArgb(0x33, 0x00, 0x00, 0x00)),
+                _ => new SolidColorBrush(Colors.Transparent)
+            };
+
+            Application.Current.Resources["WindowCaptionButtonBackgroundPressed"] = theme switch
+            {
+                ElementTheme.Dark => new SolidColorBrush(Color.FromArgb(0x66, 0xFF, 0xFF, 0xFF)),
+                ElementTheme.Light => new SolidColorBrush(Color.FromArgb(0x66, 0x00, 0x00, 0x00)),
+                _ => new SolidColorBrush(Colors.Transparent)
+            };
+
+            Application.Current.Resources["WindowCaptionButtonStrokePointerOver"] = theme switch
+            {
+                ElementTheme.Dark => new SolidColorBrush(Colors.White),
+                ElementTheme.Light => new SolidColorBrush(Colors.Black),
+                _ => new SolidColorBrush(Colors.Transparent)
+            };
+
+            Application.Current.Resources["WindowCaptionButtonStrokePressed"] = theme switch
+            {
+                ElementTheme.Dark => new SolidColorBrush(Colors.White),
+                ElementTheme.Light => new SolidColorBrush(Colors.Black),
+                _ => new SolidColorBrush(Colors.Transparent)
+            };
+
+            Application.Current.Resources["WindowCaptionBackground"] = new SolidColorBrush(Colors.Transparent);
+            Application.Current.Resources["WindowCaptionBackgroundDisabled"] = new SolidColorBrush(Colors.Transparent);
+
+            var hwnd = WinRT.Interop.WindowNative.GetWindowHandle(App.MainWindow);
+            if (hwnd == GetActiveWindow())
+            {
+                SendMessage(hwnd, WMACTIVATE, WAINACTIVE, IntPtr.Zero);
+                SendMessage(hwnd, WMACTIVATE, WAACTIVE, IntPtr.Zero);
+            }
+            else
+            {
+                SendMessage(hwnd, WMACTIVATE, WAACTIVE, IntPtr.Zero);
+                SendMessage(hwnd, WMACTIVATE, WAINACTIVE, IntPtr.Zero);
+            }
+        }
+    }
+}

code/TemplateStudioForWinUICs/Templates/_comp/MT/Project.MenuBar/Views/ShellPage.xaml.cs

@@ -34,6 +34,8 @@ public sealed partial class ShellPage : Page
 
     private void OnLoaded(object sender, RoutedEventArgs e)
     {
+        TitleBarHelper.UpdateTitleBar(RequestedTheme);
+
         KeyboardAccelerators.Add(BuildKeyboardAccelerator(VirtualKey.Left, VirtualKeyModifiers.Menu));
         KeyboardAccelerators.Add(BuildKeyboardAccelerator(VirtualKey.GoBack));
     }

code/TemplateStudioForWinUICs/Templates/_comp/MT/Project.NavView/Views/ShellPage.xaml.cs

@@ -36,6 +36,8 @@ public sealed partial class ShellPage : Page
 
     private void OnLoaded(object sender, Microsoft.UI.Xaml.RoutedEventArgs e)
     {
+        TitleBarHelper.UpdateTitleBar(RequestedTheme);
+
         KeyboardAccelerators.Add(BuildKeyboardAccelerator(VirtualKey.Left, VirtualKeyModifiers.Menu));
         KeyboardAccelerators.Add(BuildKeyboardAccelerator(VirtualKey.GoBack));
     }