private void menuItem4_Click(object sender, EventArgs e) { string message = "确认要退出重新登录吗?"; string caption = "重新登录!"; MessageBoxButtons buttons = MessageBoxButtons.YesNo; DialogResult result; // Displays the MessageBox. result = MessageBox.Show(message, caption, buttons, MessageBoxIcon.Question, MessageBoxDefaultButton.Button1); if (result == DialogResult.Yes) { this.Dispose(); this.Hide(); LoginIn lg1 = new LoginIn(); lg1.Show(); } }