Hide title bar for standalone of Unity

HideTitleBar.cs

using System;
using System.Runtime.InteropServices;
using UnityEngine;

namespace Utils
{
	public class HideTitleBar : MonoBehaviour
	{
		public static int GWL_WNDPROC = -4;
		public static int GWL_STYLE = -16;
		public static int WS_CHILD = 0x40000000;
		public static int WS_BORDER = 0x00800000;
		public static int WS_DLGFRAME = 0x00400000;
		public static int WS_CAPTION = WS_BORDER | WS_DLGFRAME;
		public static uint WM_NCCALCSIZE = 0x0083;
		private Func<IntPtr, uint, IntPtr, IntPtr, IntPtr> customWndProcDelegate;
		private IntPtr defaultWndProcPtr;
		private void Awake()
		{
#if UNITY_STANDALONE_WIN && !UNITY_EDITOR
            var window = GetActiveWindow();
            var style = GetWindowLong(window, GWL_STYLE);
            SetWindowLong(window, GWL_STYLE, style & ~WS_CAPTION);

            this.customWndProcDelegate = this.CustomWndProc;
            this.defaultWndProcPtr = SetWindowLongPtr(
                window,
                GWL_WNDPROC,
                Marshal.GetFunctionPointerForDelegate(this.customWndProcDelegate));

            SetWindowPos(
                window,
                0);
#endif
		}

#if UNITY_STANDALONE_WIN && !UNITY_EDITOR
        private IntPtr CustomWndProc(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam)
        {
            var result = CallWindowProc(this.defaultWndProcPtr, hWnd, msg, wParam, lParam);
            if ((msg == WM_NCCALCSIZE) && ((int)wParam == 1))
            {
                var ncCalcSizeParams = Marshal.PtrToStructure<NCCALCSIZE_PARAMS>(lParam);
                ncCalcSizeParams.rgrc[0].Top -= 6;
                Marshal.StructureToPtr(ncCalcSizeParams, lParam, false);
            }
            return result;
        }
#endif
		[StructLayout(LayoutKind.Sequential)]
		public struct RECT
		{
			public int Left, Top, Right, Bottom;
		}
		[StructLayout(LayoutKind.Sequential)]
		public struct WINDOWPOS
		{
			public IntPtr hwnd;
			public IntPtr hwndInsertAfter;
		}
		[StructLayout(LayoutKind.Sequential)]
		private struct NCCALCSIZE_PARAMS
		{
			[MarshalAs(UnmanagedType.ByValArray, SizeConst = 3)]
			public readonly RECT[] rgrc;
			public WINDOWPOS lppos;
		}

#if UNITY_STANDALONE_WIN && !UNITY_EDITOR
        [DllImport("user32.dll", EntryPoint = "SetWindowPos")]
        private static extern bool SetWindowPos(
            int hWnd,
            int hWndInsertAfter);

        [DllImport("user32.dll")]
        static extern int GetActiveWindow();

        [DllImport("user32.dll")]
        public static extern int SetWindowLong(int hWnd, int nIndex, int dwNewLong);

        [DllImport("user32.dll")]
        public static extern int GetWindowLong(int hWnd, int nIndex);

        [DllImport("user32.dll")]
        public static extern IntPtr SetWindowLongPtr(int hWnd, int nIndex, IntPtr dwNewLong);

        [DllImport("user32.dll")]
        private static extern IntPtr GetWindowLongPtr(int hWnd, int nIndex);

        [DllImport("user32.dll")]
        private static extern IntPtr CallWindowProc(
            IntPtr lpPrevWndFunc,
            IntPtr hWnd,
            uint Msg,
            IntPtr wParam,
            IntPtr lParam);
#endif
	}
}