winform程序关闭界面时弹出提示框

void Form1_FormClosing(object sender, FormClosingEventArgs e){    if (MessageBox.Show(            "窗口关闭后，数据即将丢失！是否现在关闭窗口",            "提示",             MessageBoxButtons.OKCancel,             MessageBoxIcon.Question) != DialogResult.OK)            {                e.Cancel = true;                return;            }}