CmdPal: Make Dock stay on top of all other windows (#46163)

<!-- Enter a brief description/summary of your PR here. What does it
fix/what does it change/how was it tested (even manually, if necessary)?
-->
## Summary of the Pull Request

This PR makes 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.

## Pictures? Pictures!

<img width="560" height="283" alt="image"
src="https://github.com/user-attachments/assets/55346005-2fac-4357-88bd-60c899565fac"
/>



https://github.com/user-attachments/assets/b81bff6d-4616-4d17-a1b0-063d254022ed


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## PR Checklist

- [x] Closes: #46161
<!-- - [ ] Closes: #yyy (add separate lines for additional resolved
issues) -->
- [ ] **Communication:** I've discussed this with core contributors
already. If the work hasn't been agreed, this work might be rejected
- [ ] **Tests:** Added/updated and all pass
- [ ] **Localization:** All end-user-facing strings can be localized
- [ ] **Dev docs:** Added/updated
- [ ] **New binaries:** Added on the required places
- [ ] [JSON for
signing](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ ] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
- [ ] [YML for CI
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
- [ ] [YML for signed
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml)
- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx

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or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments

<!-- Describe how you validated the behavior. Add automated tests
wherever possible, but list manual validation steps taken as well -->
## Validation Steps Performed

.github/actions/spell-check/allow/code.txt

@@ -339,6 +339,7 @@ SETAUTOHIDEBAR
 WINDOWPOS
 WINEVENTPROC
 WORKERW
+FULLSCREENAPP
 
 # PowerRename metadata pattern abbreviations (used in tests and regex patterns)
 DDDD

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

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

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

@@ -226,6 +226,15 @@ public partial class SettingsViewModel : INotifyPropertyChanged
         }
     }
 
+    public bool Dock_AlwaysOnTop
+    {
+        get => _settingsService.Settings.DockSettings.AlwaysOnTop;
+        set
+        {
+            _settingsService.UpdateSettings(s => s with { DockSettings = s.DockSettings with { AlwaysOnTop = value } });
+        }
+    }
+
     public bool EnableDock
     {
         get => _settingsService.Settings.EnableDock;

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

@@ -5,6 +5,7 @@
 using System.Runtime.InteropServices;
 using CommunityToolkit.Mvvm.Messaging;
 using ManagedCommon;
+using Microsoft.CmdPal.UI.Helpers;
 using Microsoft.CmdPal.UI.ViewModels;
 using Microsoft.CmdPal.UI.ViewModels.Dock;
 using Microsoft.CmdPal.UI.ViewModels.Messages;
@@ -51,6 +52,8 @@ public sealed partial class DockWindow : WindowEx,
     private HWND _hwnd = HWND.Null;
     private APPBARDATA _appBarData;
     private uint _callbackMessageId;
+    private bool _isWindowTopmost;
+    private bool _isFullScreenAppOpen;
 
     private DockSettings _settings;
     private DockViewModel viewModel;
@@ -129,6 +132,7 @@ public sealed partial class DockWindow : WindowEx,
         _ = PInvoke.SetWindowLong(_hwnd, WINDOW_LONG_PTR_INDEX.GWL_STYLE, (int)style);
 
         ShowDesktop.AddHook(this);
+        _isFullScreenAppOpen = WindowHelper.IsWindowFullscreen();
         UpdateSettingsOnUiThread();
     }
 
@@ -147,6 +151,8 @@ public sealed partial class DockWindow : WindowEx,
             BOOL value = false;
             PInvoke.DwmSetWindowAttribute(_hwnd, DWMWINDOWATTRIBUTE.DWMWA_WINDOW_CORNER_PREFERENCE, &value, (uint)sizeof(BOOL));
         }
+
+        UpdateTopmostState();
     }
 
     private HWND GetWindowHandle(Window window)
@@ -161,6 +167,7 @@ public sealed partial class DockWindow : WindowEx,
         UpdateBackdrop();
 
         _dock.UpdateSettings(_settings);
+
         var side = DockSettingsToViews.GetAppBarEdge(_settings.Side);
 
         if (_appBarData.hWnd != IntPtr.Zero)
@@ -169,6 +176,7 @@ public sealed partial class DockWindow : WindowEx,
             var sameSize = _lastSize == _settings.DockSize;
             if (sameEdge && sameSize)
             {
+                UpdateTopmostState();
                 return;
             }
 
@@ -176,6 +184,7 @@ public sealed partial class DockWindow : WindowEx,
         }
 
         CreateAppBar(_hwnd);
+        UpdateTopmostState();
     }
 
     private void InitializeBackdropSupport()
@@ -333,6 +342,41 @@ public sealed partial class DockWindow : WindowEx,
         _appBarData = default;
     }
 
+    private void UpdateTopmostState(bool bringToFront = false)
+    {
+        var shouldStayOnTop = _settings.AlwaysOnTop && !_isFullScreenAppOpen;
+        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;
+        }
+
+        var zOrder = _isFullScreenAppOpen ? HWND.HWND_BOTTOM : HWND.HWND_NOTOPMOST;
+        PInvoke.SetWindowPos(_hwnd, zOrder, 0, 0, 0, 0, flags);
+        _isWindowTopmost = false;
+    }
+
     private void UpdateWindowPosition()
     {
         Logger.LogDebug("UpdateWindowPosition");
@@ -558,6 +602,11 @@ public sealed partial class DockWindow : WindowEx,
             {
                 UpdateWindowPosition();
             }
+            else if (wParam.Value == PInvoke.ABN_FULLSCREENAPP)
+            {
+                _isFullScreenAppOpen = lParam != 0;
+                UpdateTopmostState();
+            }
         }
         else if (msg == WM_TASKBAR_RESTART)
         {
@@ -576,9 +625,7 @@ public sealed partial class DockWindow : WindowEx,
     {
         DispatcherQueue.TryEnqueue(() =>
         {
-            var onTop = message.OnTop ? HWND.HWND_TOPMOST : HWND.HWND_NOTOPMOST;
+            UpdateTopmostState(message.BringToFront);
-            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);
         });
     }
 
@@ -770,18 +817,20 @@ internal static class ShowDesktop
         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/NativeMethods.txt

@@ -76,6 +76,7 @@ ABM_REMOVE
 ABM_SETAUTOHIDEBAR
 ABS_AUTOHIDE
 ABN_POSCHANGED
+ABN_FULLSCREENAPP
 APPBARDATA
 ABE_TOP
 ABE_BOTTOM

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}" />
 

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

@@ -464,6 +464,12 @@ 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>