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codice:
    public partial class Form1 : Form
    {
        public static string Color;
        public Form1()
        {
            InitializeComponent();
        }
        private void Form1_Load(object sender, EventArgs e)
        {
            comboBox1.Items.Add("White");
            comboBox1.Items.Add("Black");
        }
        private void comboBox1_Click(object sender, EventArgs e)
        {
            Form2 Form2 = new Form2();
            Color = comboBox1.Text;
            Form2.Show();
        }
    }


    public partial class Form2 : Form
    {
        public Form2()
        {
            InitializeComponent();
        }
        private void Form2_Load(object sender, EventArgs e)
        {
            if (Form1.Color == "White")
                pictureBox1.BackColor = Color.White;
            else
                pictureBox1.BackColor = Color.Black;
        }
    }