怎么用C#编程,让键盘不起作用?

让键盘不起作用：必须指定某一个控件或者某一个窗体
这样写：
就是在控件或者窗体的KeyPress事件里写：
e.Handled = true;

下面是个例子：
在一个窗体上放一个TextBox控件txtTest和一个计时控件timerTest 计时十秒

private void TestForm_Load(object sender, EventArgs e)
{
txtTest.KeyPress += new KeyPressEventHandler(txtTest_KeyPress);
timerTest.Enabled = true;
}

void txtTest_KeyPress(object sender, KeyPressEventArgs e)
{
e.Handled = true;
}

private void timerTest_Tick(object sender, EventArgs e)
{
txtTest.KeyPress -= new KeyPressEventHandler(txtTest_KeyPress);
}

//
// txtTest
//
this.txtTest.Location = new System.Drawing.Point(117, 78);
this.txtTest.Name = "txtTest";
this.txtTest.Size = new System.Drawing.Size(100, 21);
this.tx