private void Themebox_SelectedIndexChanged_1(object sender, EventArgs e) { if (Themebox.SelectedIndex == 0) { subject.Changed(Observerlbl.Text = "Red"); this.BackColor = Color.Red; } else if (Themebox.SelectedIndex == 1) { subject.Changed(Observerlbl.Text = "Blue"); this.BackColor = Color.Blue; } }