Bug fix: use dispatcher to apply theme

CPAP-Exporter.UI/CpapExporterThemeDetector.cs

@@ -0,0 +1,47 @@
+using System.Windows;
+
+namespace CascadePass.CPAPExporter
+{
+    public class CpapExporterThemeDetector : ThemeDetector
+    {
+        public CpapExporterThemeDetector() : base()
+        {
+        }
+
+        public CpapExporterThemeDetector(IRegistryProvider registryProviderToUse) : base(registryProviderToUse)
+        {
+        }
+
+        public override bool ApplyTheme()
+        {
+            if (Application.Current?.Dispatcher is null)
+            {
+                // This is probably a unit test.
+                return false;
+            }
+
+            Application.Current.Dispatcher.Invoke(() =>
+            {
+
+                Application.Current.Resources.MergedDictionaries.Clear();
+
+                var currentTheme = this.GetThemeType();
+                if (currentTheme == ThemeType.Dark)
+                {
+                    Application.Current.Resources.MergedDictionaries.Add(new() { Source = new Uri("/Themes/Dark.xaml", UriKind.Relative) });
+                }
+                else if (currentTheme == ThemeType.Light)
+                {
+                    Application.Current.Resources.MergedDictionaries.Add(new() { Source = new Uri("/Themes/Light.xaml", UriKind.Relative) });
+                }
+
+                Application.Current.Resources.MergedDictionaries.Add(new() { Source = new Uri("/Fonts.xaml", UriKind.Relative) });
+                Application.Current.Resources.MergedDictionaries.Add(new() { Source = new Uri("/Styles.xaml", UriKind.Relative) });
+
+                Application.Current.Resources.MergedDictionaries.Add(new() { Source = new Uri("pack://application:,,,/PresentationFramework.Fluent;component/Themes/Fluent.xaml", UriKind.Absolute) });
+            });
+
+            return true;
+        }
+    }
+}

CPAP-Exporter.UI/ThemeDetector.cs

@@ -1,9 +1,4 @@
 using Microsoft.Win32;
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
 using System.Windows;
 
 namespace CascadePass.CPAPExporter
@@ -94,42 +89,6 @@ protected async void OnThemeChanged(object sender, EventArgs e)
         #endregion
     }
 
-    public class CpapExporterThemeDetector : ThemeDetector
-    {
-        public CpapExporterThemeDetector() : base()
-        {
-        }
-
-        public CpapExporterThemeDetector(IRegistryProvider registryProviderToUse) : base(registryProviderToUse)
-        {
-        }
-
-        public override bool ApplyTheme()
-        {
-            // Implement the logic to apply the theme based on the current system settings.
-
-            Application.Current.Resources.MergedDictionaries.Clear();
-
-            var currentTheme = this.GetThemeType();
-            if (currentTheme == ThemeType.Dark)
-            {
-                Application.Current.Resources.MergedDictionaries.Add(new() { Source = new Uri("/Themes/Dark.xaml", UriKind.Relative) });
-            }
-            else if (currentTheme == ThemeType.Light)
-            {
-                Application.Current.Resources.MergedDictionaries.Add(new() { Source = new Uri("/Themes/Light.xaml", UriKind.Relative) });
-            }
-
-            Application.Current.Resources.MergedDictionaries.Add(new() { Source = new Uri("/Fonts.xaml", UriKind.Relative) });
-            Application.Current.Resources.MergedDictionaries.Add(new() { Source = new Uri("/Styles.xaml", UriKind.Relative) });
-
-            Application.Current.Resources.MergedDictionaries.Add(new() { Source = new Uri("pack://application:,,,/PresentationFramework.Fluent;component/Themes/Fluent.xaml", UriKind.Absolute) });
-            //base.ThemeChanged?.Invoke(this, EventArgs.Empty);
-
-            return true;
-        }
-    }
-
     /// <summary>
     /// Represents a type or category of theme, of which there can be many individual
     /// themes.  Applications typically implement their own themes, sometimes many;