From d258dcd61bd2496739c70fb4237202f5765a7072 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ji=C5=99=C3=AD=20Pol=C3=A1=C5=A1ek?= <me@jiripolasek.com>
Date: Sat, 12 Jul 2025 21:38:01 +0200
Subject: [PATCH] CmdPal: Remove backdrop targets from existing backdrop
 controller before assigning a new one (#40540)

## Summary of the Pull Request
Also runs the code through UI thread. it will ensure correct access to
_acrylicController, and also because the method touches UI element.


<!-- Please review the items on the PR checklist before submitting-->
## PR Checklist

- [x] **Closes:** #38659
- [ ] **Communication:** I've discussed this with core contributors
already. If the work hasn't been agreed, this work might be rejected
- [x] **Tests:** Added/updated and all pass
- [x] **Localization:** All end-user-facing strings can be localized
- [x] **Dev docs:** Added/updated
- [x] **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)
- [x] **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

<!-- Provide a more detailed description of the PR, other things fixed,
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
---
 src/modules/cmdpal/Microsoft.CmdPal.UI/MainWindow.xaml.cs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/modules/cmdpal/Microsoft.CmdPal.UI/MainWindow.xaml.cs b/src/modules/cmdpal/Microsoft.CmdPal.UI/MainWindow.xaml.cs
index 3020c85859..ec82d3357e 100644
--- a/src/modules/cmdpal/Microsoft.CmdPal.UI/MainWindow.xaml.cs
+++ b/src/modules/cmdpal/Microsoft.CmdPal.UI/MainWindow.xaml.cs
@@ -107,7 +107,7 @@ public sealed partial class MainWindow : WindowEx,
         App.Current.Services.GetService<SettingsModel>()!.SettingsChanged += SettingsChangedHandler;
 
         // Make sure that we update the acrylic theme when the OS theme changes
-        RootShellPage.ActualThemeChanged += (s, e) => UpdateAcrylic();
+        RootShellPage.ActualThemeChanged += (s, e) => DispatcherQueue.TryEnqueue(UpdateAcrylic);
 
         // Hardcoding event name to avoid bringing in the PowerToys.interop dependency. Event name must match CMDPAL_SHOW_EVENT from shared_constants.h
         NativeEventWaiter.WaitForEventLoop("Local\\PowerToysCmdPal-ShowEvent-62336fcd-8611-4023-9b30-091a6af4cc5a", () =>
@@ -175,6 +175,8 @@ public sealed partial class MainWindow : WindowEx,
 
     private void UpdateAcrylic()
     {
+        _acrylicController?.RemoveAllSystemBackdropTargets();
+
         _acrylicController = GetAcrylicConfig(Content);
 
         // Enable the system backdrop.