---

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;

namespace WindowsFormsApp1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            this.DoubleBuffered = true;
        }

        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            Random rand = new Random();
            for (int i = 0; i < 50; ++i)
            {
                int w = rand.Next(10, 100);
                int h = rand.Next(10, 100);
                int x = rand.Next(this.ClientSize.Width - w);
                int y = rand.Next(this.ClientSize.Height - h);
                using (SolidBrush brush = new SolidBrush(Color.FromArgb(rand.Next(256), rand.Next(256), rand.Next(256))))
                    e.Graphics.FillRectangle(brush, x, y, w, h);
                using (Pen pen = new Pen(Color.Black, 1))
                    e.Graphics.DrawRectangle(pen, x, y, w, h);
            }
        }

        private void Form1_Resize(object sender, EventArgs e)
        {
            Invalidate();
        }
    }
}