Five yellow squares with different alpha values(Transparensy)

   
  

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;

public class Form1 : System.Windows.Forms.Form
{
  [STAThread]
  static void Main() 
  {
    Application.Run(new Form1());
  }
  protected override void OnPaint(PaintEventArgs e)
  {
    Graphics g;
    g = Graphics.FromHwnd(this.Handle);

    g.FillRectangle(new SolidBrush(Color.Red), 10, 10, 210, 50);

    // 
    Rectangle r = new Rectangle(40, 20, 30, 30);
    Color c = Color.FromArgb(255, 255, 255, 0);
    g.FillRectangle(new SolidBrush(c), r);

    r.Offset(30, 0);
    c = Color.FromArgb(200, 255, 255, 0);
    g.FillRectangle(new SolidBrush(c), r);

    r.Offset(30, 0);
    c = Color.FromArgb(150, 255, 255, 0);
    g.FillRectangle(new SolidBrush(c), r);

    r.Offset(30, 0);
    c = Color.FromArgb(100, 255, 255, 0);
    g.FillRectangle(new SolidBrush(c), r);

    r.Offset(30, 0);
    c = Color.FromArgb(50, 255, 255, 0);
    g.FillRectangle(new SolidBrush(c), r);

    g.Dispose();    
  }
}