In order to lock your computer, you need to use the following two APIs:
[DllImport("user32.dll")]
public static extern void LockWorkStation();
[DllImport("user32.dll")]
public static extern int ExitWindowsEx(int uFlags, int dwReason);
You should implement it as follows:
// Lock computer
void btnLock_Click(object sender, System.EventArgs e)
{
LockWorkStation();
}
// Log Off
void btnLogOff_Click(object sender, System.EventArgs e)
{
if(DialogResult.Yes==MessageBox.Show("Log Off?","Log Off", MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button2))
ExitWindowsEx(0, 0);
}
// Shutdown
void btnShutdown_Click(object sender, System.EventArgs e)
{
if(DialogResult.Yes==MessageBox.Show("Shutdown?","Shutdown", MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button2))
ExitWindowsEx(1, 0 );