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

namespace WHITEBOX
{
    public partial class Form1 : Form
    {
        [DllImport("User32.dll")]
        public static extern IntPtr GetDC(IntPtr hwnd);
        [DllImport("User32.dll")]
        public static extern void ReleaseDC(IntPtr hwnd, IntPtr dc);
        public Form1()
        {
            InitializeComponent();
        }

        private void tmrRefresh_Tick(object sender, EventArgs e)
        {
            this.Hide();
            tmrRefresh.Interval = 1;
            IntPtr desktopPtr = GetDC(IntPtr.Zero);
            Graphics g = Graphics.FromHdc(desktopPtr);
            int iXScreen = 1920;
            int iYScreen = 1080;
            int iXSize = 240;
            int iYSize = 240;
            int iX = (iXScreen / 2) - (iXSize / 2);
            int iY = (iYScreen / 2) - (iYSize / 2);
            Pen P = new Pen(Color.White, 1);
            Rectangle rect = new Rectangle(iX, iY, iXSize, iYSize);
            g.DrawRectangle(P, rect);
            g.Dispose();
            ReleaseDC(IntPtr.Zero, desktopPtr);
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            this.Hide();
            tmrRefresh.Enabled = true;
        }
    }
}

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

namespace WHITEBOX
{
    public partial class Form1 : Form
    {
        [DllImport("User32.dll")]
        public static extern IntPtr GetDC(IntPtr hwnd);
        [DllImport("User32.dll")]
        public static extern void ReleaseDC(IntPtr hwnd, IntPtr dc);
        public Form1()
        {
            InitializeComponent();
        }

        private void tmrRefresh_Tick(object sender, EventArgs e)
        {
            this.Hide();
            tmrRefresh.Interval = 1;
            IntPtr desktopPtr = GetDC(IntPtr.Zero);
            Graphics g = Graphics.FromHdc(desktopPtr);
            int iXScreen = 1920;
            int iYScreen = 1080;
            int iXSize = 240;
            int iYSize = 240;
            int iX = (iXScreen / 2) - (iXSize / 2);
            int iY = (iYScreen / 2) - (iYSize / 2);
            Pen P = new Pen(Color.White, 1);
            Rectangle rect = new Rectangle(iX, iY, iXSize, iYSize);
            g.DrawRectangle(P, rect);
            g.Dispose();
            ReleaseDC(IntPtr.Zero, desktopPtr);
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            this.Hide();
            tmrRefresh.Enabled = true;
        }
    }
}