Dropdown list...easy one..

private void button1_Click(object sender, System.EventArgs e) { if (this.comboBox1.Text != null && this.comboBox1.Text != "") { if (this.comboBox1.Items.IndexOf(this.comboBox1.Text) != -1) { this.DialogResult = DialogResult.OK; Close(); } else { MessageBox.Show(this, "Just select, do not enter text"); return; } } else { MessageBox.Show(this, "You have to select something"); return; } } private void Form_Load(...) { //filling comboBox1 with items..... // after filling complete: this.comboBox1.SelectedIndex = 1; }