Handle system close command to open Shut Down Windows dialog box

Just like the stock taskbar does.

Author: xoascf

RetroBar/Taskbar.xaml.cs

@@ -226,6 +226,11 @@ protected override IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lP
             {
                 windowManager.NotifyWorkAreaChange();
             }
+            else if (msg == (int)NativeMethods.WM.SYSCOMMAND && wParam == (IntPtr)NativeMethods.SC_CLOSE)
+            {
+                IntPtr progmanHwnd = NativeMethods.FindWindow("Progman", "Program Manager");
+                NativeMethods.SendMessage(progmanHwnd, (int)NativeMethods.WM.CLOSE, IntPtr.Zero, IntPtr.Zero);
+            }
 
             return IntPtr.Zero;
         }