Координаты курсора на разных экранах

e.Graphics.DrawImage(image, rect, rectBound, GraphicsUnit.Point);

        private void pictureBox1_Paint(object sender, PaintEventArgs e)
        {
            Size screensize = new Size(1280, 1024);
            var rec = new Rectangle((int)Math.Round(900D * ((double)pictureBox1.Width / (double)screensize.Width)),
                    (int)Math.Round(720D * ((double)pictureBox1.Height / (double)screensize.Height)),
                    (int)Math.Round(50D * ((double)pictureBox1.Width / (double)screensize.Width)),
                    (int)Math.Round(110D * ((double)pictureBox1.Height / (double)screensize.Height)));
                e.Graphics.DrawRectangle(Pens.Red, rec);
                e.Graphics.Flush();
        }

        private void pictureBox1_MouseClick(object sender, MouseEventArgs e)
        {
            Size screensize = new Size(1280, 1024);
            var rec = new Rectangle((int)Math.Round(900D * ((double)pictureBox1.Width / (double)screensize.Width)),
                    (int)Math.Round(720D * ((double)pictureBox1.Height / (double)screensize.Height)),
                    (int)Math.Round(50D * ((double)pictureBox1.Width / (double)screensize.Width)),
                    (int)Math.Round(110D * ((double)pictureBox1.Height / (double)screensize.Height)));
            if (rec.Contains(e.Location))
            {
                MessageBox.Show("Попал!");
            }
        }