using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace test
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        [DllImport("dwmapi.dll", PreserveSig = false)]
        public static extern bool DwmIsCompositionEnabled();
        [DllImport("dwmapi.dll", PreserveSig = false)]
        public static extern void DwmExtendFrameIntoClientArea(IntPtr hWnd, ref MARGINS pMargins);
        [StructLayout(LayoutKind.Sequential)]
        public struct MARGINS
        {
            public int Left;
            public int Right;
            public int Top;
            public int Bottom;
        }        
        
        private void Form1_Load(object sender, EventArgs e)
        {
            // Form上にはlabelやtextboxを適当に配置して
            this.BackColor = Color.Black;
            if (DwmIsCompositionEnabled())
            {
                MARGINS margin = new MARGINS();
                margin.Top = -1;
                margin.Right = 0;
                margin.Left = 0;
                margin.Bottom = 0;
                DwmExtendFrameIntoClientArea(this.Handle, ref margin);
            }
        }
    }
}