Make Dock stay on top of all other windows

- Marks the Dock window as topmost when there is no full-screen window.
- Adds a new option that allows the user to disable this behavior.
- Adds a timer that polls the system API to determine whether a full-screen window is present.

Author: jiripolasek

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/Settings/DockSettings.cs

@@ -22,6 +22,8 @@ public class DockSettings
 
     public DockSize DockIconsSize { get; set; } = DockSize.Small;
 
+    public bool AlwaysOnTop { get; set; } = true;
+
     // <Theme settings>
     public DockBackdrop Backdrop { get; set; } = DockBackdrop.Acrylic;
 

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/SettingsViewModel.cs

@@ -227,6 +227,16 @@ public bool Dock_ShowLabels
         }
     }
 
+    public bool Dock_AlwaysOnTop
+    {
+        get => _settings.DockSettings.AlwaysOnTop;
+        set
+        {
+            _settings.DockSettings.AlwaysOnTop = value;
+            Save();
+        }
+    }
+
     public bool EnableDock
     {
         get => _settings.EnableDock;

src/modules/cmdpal/Microsoft.CmdPal.UI/Dock/DockWindow.xaml.cs

@@ -39,6 +39,8 @@ public sealed partial class DockWindow : WindowEx,
     IRecipient<QuitMessage>,
     IDisposable
 {
+    private static readonly TimeSpan TopmostStateRefreshInterval = TimeSpan.FromSeconds(1);
+
 #pragma warning disable SA1306 // Field names should begin with lower-case letter
 #pragma warning disable SA1310 // Field names should not contain underscore
     private readonly uint WM_TASKBAR_RESTART;
@@ -49,9 +51,13 @@ public sealed partial class DockWindow : WindowEx,
     private readonly DockWindowViewModel _windowViewModel;
     private readonly HiddenOwnerWindowBehavior _hiddenOwnerWindowBehavior = new();
 
+    // SHQueryUserNotificationState does not raise change notifications, so we poll lightly.
+    private readonly DispatcherTimer _topmostStateTimer = new();
+
     private HWND _hwnd = HWND.Null;
     private APPBARDATA _appBarData;
     private uint _callbackMessageId;
+    private bool _isWindowTopmost;
 
     private DockSettings _settings;
     private DockViewModel viewModel;
@@ -91,6 +97,8 @@ public DockWindow()
         }
 
         this.Activated += DockWindow_Activated;
+        _topmostStateTimer.Interval = TopmostStateRefreshInterval;
+        _topmostStateTimer.Tick += TopmostStateTimer_Tick;
 
         WeakReferenceMessenger.Default.Register<BringToTopMessage>(this);
         WeakReferenceMessenger.Default.Register<RequestShowPaletteAtMessage>(this);
@@ -143,6 +151,13 @@ private void DockWindow_Activated(object sender, WindowActivatedEventArgs args)
             BOOL value = false;
             PInvoke.DwmSetWindowAttribute(_hwnd, DWMWINDOWATTRIBUTE.DWMWA_WINDOW_CORNER_PREFERENCE, &value, (uint)sizeof(BOOL));
         }
+
+        UpdateTopmostState();
+    }
+
+    private void TopmostStateTimer_Tick(object? sender, object e)
+    {
+        UpdateTopmostState();
     }
 
     private HWND GetWindowHandle(Window window)
@@ -164,6 +179,18 @@ private void UpdateSettingsOnUiThread()
         }
 
         _dock.UpdateSettings(_settings);
+
+        // Only poll for fullscreen changes when AlwaysOnTop is active;
+        // when disabled the timer is unnecessary work.
+        if (_settings.AlwaysOnTop)
+        {
+            _topmostStateTimer.Start();
+        }
+        else
+        {
+            _topmostStateTimer.Stop();
+        }
+
         var side = DockSettingsToViews.GetAppBarEdge(_settings.Side);
 
         if (_appBarData.hWnd != IntPtr.Zero)
@@ -172,13 +199,15 @@ private void UpdateSettingsOnUiThread()
             var sameSize = _lastSize == _settings.DockSize;
             if (sameEdge && sameSize)
             {
+                UpdateTopmostState();
                 return;
             }
 
             DestroyAppBar(_hwnd);
         }
 
         CreateAppBar(_hwnd);
+        UpdateTopmostState();
     }
 
     // We want to use DesktopAcrylicKind.Thin and custom colors as this is the default material
@@ -278,6 +307,40 @@ private void DestroyAppBar(HWND hwnd)
         _appBarData = default;
     }
 
+    private void UpdateTopmostState(bool bringToFront = false)
+    {
+        var shouldStayOnTop = _settings.AlwaysOnTop && !WindowHelper.IsWindowFullscreen();
+        const SET_WINDOW_POS_FLAGS flags = SET_WINDOW_POS_FLAGS.SWP_NOMOVE | SET_WINDOW_POS_FLAGS.SWP_NOSIZE | SET_WINDOW_POS_FLAGS.SWP_NOACTIVATE;
+
+        if (shouldStayOnTop)
+        {
+            if (_isWindowTopmost && !bringToFront)
+            {
+                return;
+            }
+
+            PInvoke.SetWindowPos(_hwnd, HWND.HWND_TOPMOST, 0, 0, 0, 0, flags);
+            _isWindowTopmost = true;
+            return;
+        }
+
+        if (bringToFront)
+        {
+            // Win32 trick: briefly set HWND_TOPMOST then immediately clear it
+            // with HWND_NOTOPMOST. This brings the window to the foreground
+            // without permanently pinning it as topmost.
+            PInvoke.SetWindowPos(_hwnd, HWND.HWND_TOPMOST, 0, 0, 0, 0, flags);
+        }
+
+        if (!_isWindowTopmost && !bringToFront)
+        {
+            return;
+        }
+
+        PInvoke.SetWindowPos(_hwnd, HWND.HWND_NOTOPMOST, 0, 0, 0, 0, flags);
+        _isWindowTopmost = false;
+    }
+
     private void UpdateWindowPosition()
     {
         Logger.LogDebug("UpdateWindowPosition");
@@ -521,9 +584,7 @@ void IRecipient<BringToTopMessage>.Receive(BringToTopMessage message)
     {
         DispatcherQueue.TryEnqueue(() =>
         {
-            var onTop = message.OnTop ? HWND.HWND_TOPMOST : HWND.HWND_NOTOPMOST;
-            PInvoke.SetWindowPos(_hwnd, onTop, 0, 0, 0, 0, SET_WINDOW_POS_FLAGS.SWP_NOMOVE | SET_WINDOW_POS_FLAGS.SWP_NOSIZE);
-            PInvoke.SetWindowPos(_hwnd, HWND.HWND_NOTOPMOST, 0, 0, 0, 0, SET_WINDOW_POS_FLAGS.SWP_NOMOVE | SET_WINDOW_POS_FLAGS.SWP_NOSIZE);
+            UpdateTopmostState(message.BringToFront);
         });
     }
 
@@ -615,6 +676,8 @@ private void RequestShowPaletteOnUiThread(Point posDips)
 
     public void Dispose()
     {
+        _topmostStateTimer.Stop();
+        _topmostStateTimer.Tick -= TopmostStateTimer_Tick;
         DisposeAcrylic();
         _windowViewModel.Dispose();
     }
@@ -625,6 +688,8 @@ private void DockWindow_Closed(object sender, WindowEventArgs args)
         var settings = serviceProvider.GetService<SettingsModel>();
         settings?.SettingsChanged -= SettingsChangedHandler;
         _themeService.ThemeChanged -= ThemeService_ThemeChanged;
+        _topmostStateTimer.Stop();
+        _topmostStateTimer.Tick -= TopmostStateTimer_Tick;
         DisposeAcrylic();
 
         // Remove our app bar registration
@@ -697,18 +762,20 @@ private static void WinEventCallback(
         if (eventType == PInvoke.EVENT_SYSTEM_FOREGROUND)
         {
             var @class = GetWindowClass(hwnd);
-            if (string.Equals(@class, WORKERW, StringComparison.Ordinal) || string.Equals(@class, PROGMAN, StringComparison.Ordinal))
+            var bringToFront = string.Equals(@class, WORKERW, StringComparison.Ordinal) || string.Equals(@class, PROGMAN, StringComparison.Ordinal);
+            if (bringToFront)
             {
                 Logger.LogDebug("ShowDesktop invoked. Bring us back");
-                WeakReferenceMessenger.Default.Send<BringToTopMessage>(new(true));
             }
+
+            WeakReferenceMessenger.Default.Send<BringToTopMessage>(new(bringToFront));
         }
     }
 
     public static bool IsHooked { get; private set; }
 }
 
-internal sealed record BringToTopMessage(bool OnTop);
+internal sealed record BringToTopMessage(bool BringToFront);
 
 internal sealed record RequestShowPaletteAtMessage(Point PosDips);
 

src/modules/cmdpal/Microsoft.CmdPal.UI/Settings/DockSettingsPage.xaml

@@ -212,6 +212,13 @@
                         </controls:SettingsExpander.Items>
                     </controls:SettingsExpander>
 
+                    <!--  Behavior Section  -->
+                    <TextBlock x:Uid="BehaviorSettingsHeader" Style="{StaticResource SettingsSectionHeaderTextBlockStyle}" />
+
+                    <controls:SettingsCard x:Uid="DockBehavior_AlwaysOnTop_SettingsCard" HeaderIcon="{ui:FontIcon Glyph=&#xE840;}">
+                        <ToggleSwitch IsOn="{x:Bind ViewModel.Dock_AlwaysOnTop, Mode=TwoWay}" />
+                    </controls:SettingsCard>
+
                     <!--  Bands Section  -->
                     <!--  <TextBlock x:Uid="DockBandsSettingsHeader" Style="{StaticResource SettingsSectionHeaderTextBlockStyle}" />
 
@@ -246,4 +253,4 @@
             </Grid>
         </ScrollViewer>
     </Grid>
-</Page>
+</Page>

src/modules/cmdpal/Microsoft.CmdPal.UI/Strings/en-us/Resources.resw

@@ -434,6 +434,12 @@ Right-click to remove the key combination, thereby deactivating the shortcut.</v
   <data name="Settings_GeneralPage_EnableDock_SettingsCard.Description" xml:space="preserve">
     <value>Enable a toolbar with quick access to commands</value>
   </data>
+  <data name="DockBehavior_AlwaysOnTop_SettingsCard.Header" xml:space="preserve">
+    <value>Always stay on top</value>
+  </data>
+  <data name="DockBehavior_AlwaysOnTop_SettingsCard.Description" xml:space="preserve">
+    <value>Keep the dock above other windows, except while an app is fullscreen</value>
+  </data>
   <data name="BackButton.[using:Microsoft.UI.Xaml.Automation]AutomationProperties.Name" xml:space="preserve">
     <value>Back</value>
   </data>