Form1

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

namespace MapleLegends_Overlay
{
    public partial class Form1 : Form
    {

        [DllImport("user32.dll")]
        static extern IntPtr SetParent(IntPtr hwc, IntPtr hwp);

        // Define the FindWindow API function.
        [DllImport("user32.dll", EntryPoint = "FindWindow",
            SetLastError = true)]
        static extern IntPtr FindWindowByCaption(IntPtr ZeroOnly,
            string lpWindowName);

        // Define the SetWindowPos API function.
        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        static extern bool SetWindowPos(IntPtr hWnd,
            IntPtr hWndInsertAfter, int X, int Y, int cx, int cy,
            SetWindowPosFlags uFlags);

        // Define the SetWindowPosFlags enumeration.
        [Flags()]
        private enum SetWindowPosFlags : uint
        {
            SynchronousWindowPosition = 0x4000,
            DeferErase = 0x2000,
            DrawFrame = 0x0020,
            FrameChanged = 0x0020,
            HideWindow = 0x0080,
            DoNotActivate = 0x0010,
            DoNotCopyBits = 0x0100,
            IgnoreMove = 0x0002,
            DoNotChangeOwnerZOrder = 0x0200,
            DoNotRedraw = 0x0008,
            DoNotReposition = 0x0200,
            DoNotSendChangingEvent = 0x0400,
            IgnoreResize = 0x0001,
            IgnoreZOrder = 0x0004,
            ShowWindow = 0x0040,
        }

        [DllImport("user32.dll", SetLastError = true)]
        static extern uint GetWindowThreadProcessId(IntPtr hWnd, out uint processId);

        Overlay frm = new Overlay();
        public Form1()
        {
            InitializeComponent();
        }

        private void checkBox1_CheckedChanged(object sender, EventArgs e)
        {
            if(checkBox1.Checked == true)
            {

                frm.Show();
            }
            else
            {
                frm.Hide();
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            //Process p = Process.Start("c:/MapleLegendsHD/MapleLegends.exe");
            int pidint = Convert.ToInt32(PID.Text);
            Process p = Process.GetProcessById(pidint);
            Thread.Sleep(1000);
            p.WaitForInputIdle();
            SetParent(p.MainWindowHandle, GamePanel.Handle);
            SetFullScreen(true);
            // Find (the first-in-Z-order) Notepad window.
        }

        private void Form1_Layout(object sender, LayoutEventArgs e)
        {
            button1.BringToFront();
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            if(this.WindowState == FormWindowState.Maximized)
            {
                GamePanel.Size = new Size(this.Width, this.Height);
            }
            else
            {
                GamePanel.Size = new Size(728, 246);
            }

            if(MouseInfo.Checked == true)
            {
                MouseInfoLabel.Visible = true;
                Point p = GamePanel.PointToClient(Cursor.Position);
                //MouseInfoLabel.Location = p;
                MouseInfoLabel.Text = p.ToString();
            }
            else
            {
                MouseInfoLabel.Visible = false;
            }
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void FullScreen_Click(object sender, EventArgs e)
        {
            if (FullScreen.Text == "X")
                SetFullScreen(false);

            else
                SetFullScreen(true);
        }

        private bool SetFullScreen(bool ans)
        {
            if(ans == true)
            {
                this.FormBorderStyle = FormBorderStyle.None;
                this.TopMost = true;
                this.WindowState = FormWindowState.Maximized;
                FullScreen.Text = "X";
                FullScreen.ForeColor = Color.Red;
                ControlPanel.Visible = false;
            }
            else
            {
                this.FormBorderStyle = FormBorderStyle.Sizable;
                this.TopMost = false;
                this.WindowState = FormWindowState.Normal;
                FullScreen.Text = "+";
                FullScreen.ForeColor = Color.Green;
                ControlPanel.Visible = true;
            }
            return false;
        }

        private void button2_Click(object sender, EventArgs e)
        {
            /*int pidint = Convert.ToInt32(PID2.Text);
            Process p = Process.GetProcessById(pidint);
            Thread.Sleep(1000);
            p.WaitForInputIdle();
            SetParent(p.MainWindowHandle, Game2Panel.Handle);*/
        }

        private void MouseInfo_CheckedChanged(object sender, EventArgs e)
        {
            Bitmap bitmap = Screenshot(GamePanel);
            bitmap.Save("test.bmp");
            Process.Start("test.bmp");
        }

        private static Bitmap Screenshot(Control control)
        {
            Bitmap bmpScreenshot = new Bitmap(control.Width, control.Height);
            Graphics g = Graphics.FromImage(bmpScreenshot);
            Rectangle r = control.RectangleToScreen(control.ClientRectangle);
            Point p = new Point(212, 760);
            Size s = new Size(350, 45);
            g.CopyFromScreen(r.Location, Point.Empty, control.Size);
            return bmpScreenshot;
        }

        /*private void button3_Click(object sender, EventArgs e)
        {
            IntPtr hWnd = this.Handle;
            UInt32 pidint = Convert.ToUInt32(PID2.Text, 16);
            uint processid = pidint;
            uint threadid = GetWindowThreadProcessId((IntPtr)hWnd, out processid);
            if (hWnd == IntPtr.Zero)
            {
                MessageBox.Show("Could not find this process.");
                return;
            }

            // Set the window's position.
            int width = int.Parse(txtWidth.Text);
            int height = int.Parse(txtHeight.Text);
            int x = int.Parse(txtX.Text);
            int y = int.Parse(txtY.Text);
            SetWindowPos(hWnd, IntPtr.Zero, x, y, width, height, 0);
        }*/
    }
}