SendWindowCMD.cs

using System;
using System.Diagnostics;
using System.Linq;
using System.Runtime.InteropServices;

namespace SendWindowCMD
{
  class Program
  {
    [DllImport("user32.dll", CharSet = CharSet.Auto)]
    static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, IntPtr wParam, IntPtr lParam);

    const uint WmClose = 0x0010;

    static void Main(string[] args)
    {
      if (args.Any())
      {
        if (args[0].Equals("CloseMediaportal"))
        {
          CloseMediaportalWindow();
        }
      }
    }

    static void CloseMediaportalWindow()
    {
      IntPtr hWnd = IntPtr.Zero;
      foreach (Process pList in Process.GetProcesses())
      {
        if (pList.MainWindowTitle.ToLower().StartsWith("mediaportal"))
        {
          hWnd = pList.MainWindowHandle;

          if (hWnd == IntPtr.Zero)
          {
            Console.WriteLine("Window not found");
          }
          else
          {
            Console.WriteLine("Closing Mediaportal window");
            SendMessage(hWnd, WmClose, IntPtr.Zero, IntPtr.Zero);
          }
        }
      }
    }
  }
}