/// <summary>
/// Diposes the Impersonator's resources and also calls Undo()
/// </summary>
public void Dispose()
{
// Revert back to the previous user context
this.Undo();
if (this.m_ExpireTimer != null) // check for null
{
// Dipose of the Timer
this.m_ExpireTimer.Dispose();
}
// close the open handle to the authenticated account
Shell32.CloseHandle(tokenHandle);
}