VB 屏蔽CTRL+ALT+DEL键

　　我们在编程中，为了达到特殊的要求，有时需要屏蔽功能CTRL+ALT+DLE，本示例程序将教你如何实现它。
　　实现步骤：
　　1．建立一个新项目，将其命名为DEMO3.vbp。
　　2．在Form1窗体的声明中加入以下代码：
Private Declare Function SystemParametersInfo Lib "user32" Alias "SystemParametersInfoA" (ByVal uAction As Long, ByVal uParam As Long, ByRef lpvParam As Any, ByVal fuWinIni As Long) As Long
Const SPI_SCREENSAVERRUNNING = 97
　　3． 在Form1窗口的Command1_Click中加入以下代码：
Private Sub Command1_Click()
Dim r As Integer
Dim p As Boolean
If Command1.Caption = "屏蔽" Then
r = SystemParametersInfo(SPI_SCREENSAVERRUNNING, True, p, 0)
Command1.Caption = "有效"
Else
r = SystemParametersInfo(SPI_SCREENSAVERRUNNING, False, p, 0)
Command1.Caption = "屏蔽"
End If
End Sub
　　4． 在Form1窗体的Form_Unload中加入以下代码：
Form1_Unload()
Dim r As Integer
Dim p As Boolean
r = SystemParametersInfo(SPI_SCREENSAVERRUNNING, False, p, 0)