C# rysowanie w oknie , panele wlasne

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;

namespace WindowsFormsApplication2
{
    public partial class Form1 : Form
    {
        private MojPanel mp1, mp2;

        private void rysuj_Click(object sender, EventArgs e)
        {
            Graphics g = CreateGraphics();
            try
            {
                int szer = ClientRectangle.Width;
                int wys = ClientRectangle.Height;
                int r = 40;
                g.DrawEllipse(Pens.Red, szer / 2 - r, wys / 2 - r, 2 * r, 2 * r);

            }
            finally
            {
                g.Dispose();
            }
        }
        public Form1()
        {
            //OnClick += new EventHandler(rysuj_Click);
            mp1 = new MojPanel(this, 50, 50, 100, 100, Color.Blue);
            mp2 = new MojPanel(this, 400, 400, 200, 200, Color.LightGray);


            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void rysuj2_Click(object sender, EventArgs e)
        {
            using (Graphics g = CreateGraphics())
            {
                int szer = ClientRectangle.Width;
                int wys = ClientRectangle.Height;
                int bok = 50;
                g.DrawRectangle(Pens.Blue, szer / 2, wys / 2, bok, bok);
            }
        }

        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            Graphics g = e.Graphics;
            int szer = ClientRectangle.Width;
            int wys = ClientRectangle.Height;
            int oczko = 10;
            int marg = 20;

            for (int i = marg; i <= wys - marg; i += 10)
            {
                for (int j = marg; j <= szer - marg; j += 10)
                {
                    SolidBrush b = new SolidBrush(Color.FromArgb(i % 256, j % 256, 200));
                    g.DrawRectangle(Pens.Black, j, i, oczko, oczko);
                    g.FillRectangle(b, j, i, oczko, oczko);
                }
            }
        }


        private void Form1_Resize(object sender, EventArgs e)
        {
            Invalidate();
        }
    }
    public class MojPanel : Panel
    {
        public MojPanel(Form aparent, int x, int y, int szer, int wys, Color k)
        {

            Parent = aparent;
            Left = x;
            Top = y;
            Width = szer;
            Height = wys;
            BackColor = k;
        }
        protected override void OnPaint(PaintEventArgs e)
        {
            int szer = ClientRectangle.Width;
            int wys = ClientRectangle.Height;
            Graphics g = e.Graphics;
            g.DrawLine(Pens.Azure, 0, wys, szer, 0);

        }
    }
}
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