private void btnSelectConfig_Click(object sender, EventArgs e) { if (DialogResult.OK == openFileDialog.ShowDialog()) { var xmlConfig = new XmlConfig { ConfigFile = openFileDialog.FileName }; List <string> connections = xmlConfig.GetChildElements("//connectionStrings", "connectionString"); if (connections.Count > 0) { var frm = new SaveConnectionAsForm(); if (DialogResult.OK == frm.ShowDialog()) { XmlConfig.Instance.SetValue("//MyConnectionStrings//add[@key='" + frm.ConnectionName + "']", connections[0]); DialogResult = DialogResult.OK; } } else { MessageBox.Show("No connection string found in this configuration file.", "Error!", MessageBoxButtons.OK, MessageBoxIcon.Error); } Close(); } }