using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Text;using System.Windows.Forms;namespace WindowsApplication2{  public partial class Form5 : Form  {    bool drawElipse = false;    public Form5()    {      InitializeComponent();      this.SetStyle(ControlStyles.ResizeRedraw, true);    }    private void Form5_Load(object sender, EventArgs e)    {    }    private void button1_Click(object sender, EventArgs e)    {      this.drawElipse = !this.drawElipse;      this.Invalidate(true);    }    private void Form5_Paint(object sender, PaintEventArgs e)    {      if (!this.drawElipse) return;      Graphics g = e.Graphics;      g.FillEllipse(Brushes.DarkBlue, this.ClientRectangle);    }  }}