public Form1()
{
InitializeComponent();
this.ControlBox = false;   // 設置不出現關閉按鈕
}

//禁用窗體的關閉按鈕       
private const int CP_NOCLOSE_BUTTON = 0x200;
protected override CreateParams CreateParams
{
get
{
CreateParams myCp = base.CreateParams;
myCp.ClassStyle = myCp.ClassStyle | CP_NOCLOSE_BUTTON;             
return myCp;     
}
}

private void Form1_Closing(object sender, System.ComponentModel.CancelEventArgs e)
{
e.Cancel = true;
}
// 重寫OnClosing使點擊關閉按鍵時窗體能夠縮進托盤
protected override void OnClosing(CancelEventArgs e)
{
this.ShowInTaskbar = false;
this.WindowState = FormWindowState.Minimized;
e.Cancel = true;
}