CmdPal / Settings: Prevent shortcut dialogs invocation from crashing the parent app (#49334)

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fix/what does it change/how was it tested (even manually, if necessary)?
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## Summary of the Pull Request

It looks like, when the stars align, changing the system theme can cause
the ContentDialog to open multiple times, especially if the user
repeatedly clicks the button that opens it.

- Adds a ThreadStatic flag to ensure the dialog is opened only once.
- Adds a try/catch guard in case my assumption about the flag is wrong.

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## PR Checklist

- [x] Closes: #49310
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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
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pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
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- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
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and link it here: #xxx

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

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wherever possible, but list manual validation steps taken as well -->
## Validation Steps Performed

src/modules/cmdpal/Microsoft.CmdPal.UI/Controls/ShortcutControl/ShortcutControl.xaml.cs

@@ -4,6 +4,7 @@
 
 using CommunityToolkit.Mvvm.Messaging;
 using CommunityToolkit.WinUI;
+using ManagedCommon;
 using Microsoft.CmdPal.UI.Library;
 using Microsoft.CmdPal.UI.ViewModels.Settings;
 using Microsoft.PowerToys.Settings.UI.Helpers;
@@ -28,6 +29,9 @@ public sealed partial class ShortcutControl : UserControl, IDisposable, IRecipie
     private bool _isActive;
     private bool disposedValue;
 
+    [ThreadStatic]
+    private static bool _isDialogOpen;
+
     public string Header { get; set; } = string.Empty;
 
     public string Keys { get; set; } = string.Empty;
@@ -404,16 +408,33 @@ public sealed partial class ShortcutControl : UserControl, IDisposable, IRecipie
 
     private async void OpenDialogButton_Click(object sender, RoutedEventArgs e)
     {
-        // c.Keys = null;
-        c.Keys = HotkeySettings?.GetKeysList() ?? new List<object>();
+        if (_isDialogOpen)
+        {
+            return;
+        }
 
-        // 92 means the Win key. The logic is: warning should be visible if the shortcut contains Alt AND contains Ctrl AND NOT contains Win.
-        // Additional key must be present, as this is a valid, previously used shortcut shown at dialog open. Check for presence of non-modifier-key is not necessary therefore
-        c.IsWarningAltGr = c.Keys.Contains("Ctrl") && c.Keys.Contains("Alt") && !c.Keys.Contains(92);
+        _isDialogOpen = true;
+        try
+        {
+            // c.Keys = null;
+            c.Keys = HotkeySettings?.GetKeysList() ?? new List<object>();
 
-        shortcutDialog.XamlRoot = this.XamlRoot;
-        shortcutDialog.RequestedTheme = this.ActualTheme;
-        await shortcutDialog.ShowAsync();
+            // 92 means the Win key. The logic is: warning should be visible if the shortcut contains Alt AND contains Ctrl AND NOT contains Win.
+            // Additional key must be present, as this is a valid, previously used shortcut shown at dialog open. Check for presence of non-modifier-key is not necessary therefore
+            c.IsWarningAltGr = c.Keys.Contains("Ctrl") && c.Keys.Contains("Alt") && !c.Keys.Contains(92);
+
+            shortcutDialog.XamlRoot = this.XamlRoot;
+            shortcutDialog.RequestedTheme = this.ActualTheme;
+            await shortcutDialog.ShowAsync();
+        }
+        catch (Exception ex)
+        {
+            Logger.LogError("Failed to open shortcut dialog", ex);
+        }
+        finally
+        {
+            _isDialogOpen = false;
+        }
     }
 
     private void ShortcutDialog_Reset(ContentDialog sender, ContentDialogButtonClickEventArgs args)

src/settings-ui/Settings.UI/SettingsXAML/Controls/ShortcutControl/ShortcutControl.xaml.cs

@@ -7,6 +7,7 @@ using System.Collections.Generic;
 using System.ComponentModel;
 using System.Linq;
 using CommunityToolkit.WinUI;
+using ManagedCommon;
 using Microsoft.PowerToys.Settings.UI.Helpers;
 using Microsoft.PowerToys.Settings.UI.Library;
 using Microsoft.PowerToys.Settings.UI.Library.Telemetry.Events;
@@ -42,6 +43,9 @@ namespace Microsoft.PowerToys.Settings.UI.Controls
         private bool _isActive;
         private bool disposedValue;
 
+        [ThreadStatic]
+        private static bool _isDialogOpen;
+
         public string Header { get; set; }
 
         public string Keys { get; set; }
@@ -670,20 +674,37 @@ namespace Microsoft.PowerToys.Settings.UI.Controls
 
         private async void OpenDialogButton_Click(object sender, RoutedEventArgs e)
         {
-            c.Keys = null;
-            c.Keys = HotkeySettings?.GetKeysList() ?? new List<object>();
+            if (_isDialogOpen)
+            {
+                return;
+            }
 
-            c.IgnoreConflict = IgnoreConflict;
-            c.HasConflict = hotkeySettings?.HasConflict ?? false;
-            c.ConflictMessage = hotkeySettings?.ConflictDescription;
+            _isDialogOpen = true;
+            try
+            {
+                c.Keys = null;
+                c.Keys = HotkeySettings?.GetKeysList() ?? new List<object>();
 
-            // 92 means the Win key. The logic is: warning should be visible if the shortcut contains Alt AND contains Ctrl AND NOT contains Win.
-            // Additional key must be present, as this is a valid, previously used shortcut shown at dialog open. Check for presence of non-modifier-key is not necessary therefore
-            c.IsWarningAltGr = c.Keys.Contains("Ctrl") && c.Keys.Contains("Alt") && !c.Keys.Contains(92);
+                c.IgnoreConflict = IgnoreConflict;
+                c.HasConflict = hotkeySettings?.HasConflict ?? false;
+                c.ConflictMessage = hotkeySettings?.ConflictDescription;
 
-            shortcutDialog.XamlRoot = this.XamlRoot;
-            shortcutDialog.RequestedTheme = this.ActualTheme;
-            await shortcutDialog.ShowAsync();
+                // 92 means the Win key. The logic is: warning should be visible if the shortcut contains Alt AND contains Ctrl AND NOT contains Win.
+                // Additional key must be present, as this is a valid, previously used shortcut shown at dialog open. Check for presence of non-modifier-key is not necessary therefore
+                c.IsWarningAltGr = c.Keys.Contains("Ctrl") && c.Keys.Contains("Alt") && !c.Keys.Contains(92);
+
+                shortcutDialog.XamlRoot = this.XamlRoot;
+                shortcutDialog.RequestedTheme = this.ActualTheme;
+                await shortcutDialog.ShowAsync();
+            }
+            catch (Exception ex)
+            {
+                Logger.LogError("Failed to open shortcut dialog", ex);
+            }
+            finally
+            {
+                _isDialogOpen = false;
+            }
         }
 
         private void C_ResetClick(object sender, RoutedEventArgs e)