fixed .net 4.0 compile problem

src/Shared/HandyControl_Shared/Themes/Theme.cs

@@ -5,6 +5,7 @@ using System.Windows.Media;
 using HandyControl.Data;
 using HandyControl.Tools;
 using HandyControl.Tools.Helper;
+using HandyControl.Tools.Interop;
 using Microsoft.Win32;
 
 namespace HandyControl.Themes
@@ -191,25 +192,26 @@ namespace HandyControl.Themes
             {
                 if (AccentColor != null)
                 {
-                    _precSkin[ResourceToken.PrimaryColor] = AccentColor;
-                    _precSkin[ResourceToken.DarkPrimaryColor] = AccentColor;
-                    _precSkin[ResourceToken.TitleColor] = AccentColor;
-                    _precSkin[ResourceToken.SecondaryTitleColor] = AccentColor;
+                    UpdateAccentColor(AccentColor.Value);
                 }
             }
             else
             {
-                var windowGlassColor = ((SolidColorBrush) SystemParameters.WindowGlassBrush).Color;
-
-                _precSkin[ResourceToken.PrimaryColor] = windowGlassColor;
-                _precSkin[ResourceToken.DarkPrimaryColor] = windowGlassColor;
-                _precSkin[ResourceToken.TitleColor] = windowGlassColor;
-                _precSkin[ResourceToken.SecondaryTitleColor] = windowGlassColor;
+                InteropMethods.DwmGetColorizationColor(out var color, out _);
+                UpdateAccentColor(ColorHelper.ToColor(color));
             }
 
             return _precSkin;
         }
 
+        private void UpdateAccentColor(Color color)
+        {
+            _precSkin[ResourceToken.PrimaryColor] = color;
+            _precSkin[ResourceToken.DarkPrimaryColor] = color;
+            _precSkin[ResourceToken.TitleColor] = color;
+            _precSkin[ResourceToken.SecondaryTitleColor] = color;
+        }
+
         private void UpdateSkin() => MergedDictionaries[0] = GetSkin(Skin);
 
         public virtual ResourceDictionary GetTheme() => ResourceHelper.GetTheme();

src/Shared/HandyControl_Shared/Tools/Interop/InteropMethods.cs

@@ -480,6 +480,10 @@ namespace HandyControl.Tools.Interop
         [DllImport(InteropValues.ExternDll.Shell32, CallingConvention = CallingConvention.StdCall)]
         internal static extern uint SHAppBarMessage(int dwMessage, ref InteropValues.APPBARDATA pData);
 
+        [SecurityCritical]
+        [DllImport(InteropValues.ExternDll.DwmApi, EntryPoint = "DwmGetColorizationColor", PreserveSig = true)]
+        internal static extern int DwmGetColorizationColor(out uint pcrColorization, out bool pfOpaqueBlend);
+
         #endregion
 
         internal class Gdip

src/Shared/HandyControl_Shared/Tools/Interop/InteropValues.cs

@@ -18,7 +18,8 @@ namespace HandyControl.Tools.Interop
                 Kernel32 = "kernel32.dll",
                 Shell32 = "shell32.dll",
                 MsImg = "msimg32.dll",
-                NTdll = "ntdll.dll";
+                NTdll = "ntdll.dll",
+                DwmApi = "dwmapi.dll";
         }
 
         internal delegate IntPtr HookProc(int code, IntPtr wParam, IntPtr lParam);