Form1.cs

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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 Rose
{
	public partial class Rose : Form
	{
		Graphics gr;
		private static int width = Screen.PrimaryScreen.WorkingArea.Width;
		private static int height = Screen.PrimaryScreen.WorkingArea.Height;

		public Rose()
		{
			InitializeComponent();

			this.ClientSize = new Size(width, height);
			this.TransparencyKey = this.BackColor;
		}

		private void timer1_Tick(object sender, EventArgs e)
		{
			int x, y;
			Random ran = new Random();

			x = ran.Next(-10, width - 118);
			y = ran.Next(-10, height - 100);
			
			Point point = new Point(x, y);
			
			gr = CreateGraphics();
			gr.DrawImage(Properties.Resources.r, point);
		}
	}
}