winform程序關閉界面時彈出提示框

void Form1_FormClosing(object sender, FormClosingEventArgs e){    if (MessageBox.Show(            "窗口關閉后，數據即將丟失！是否現在關閉窗口",            "提示",             MessageBoxButtons.OKCancel,             MessageBoxIcon.Question) != DialogResult.OK)            {                e.Cancel = true;                return;            }}