Private Const SPI_GETSCREENSAVEACTIVE As Long  = 16&
Private Const SPIF_SENDWININICHANGE As Long  = &H2
Private Declare Function SystemParametersInfo Lib "user32" Alias "SystemParametersInfoA" (ByVal uAction As Long, ByVal uParam As Long, lpvParam As Any, ByVal fuWinIni As Long) As  Long
Public Function IsScreenSaverActive() As Boolean
    Dim lRet As Long
    Call SystemParametersInfo(SPI_GETSCREENSAVEACTIVE, 0&, lRet,  SPIF_SENDWININICHANGE)
    IsScreenSaverActive = Not (lRet = 0)
End Function

Private Const SPI_GETSCREENSAVEACTIVE As UInteger = 16UI
Private Const SPIF_SENDWININICHANGE As UInteger = &H2UI

<System.Runtime.InteropServices.DllImport("user32.dll")> _
Private Function SystemParametersInfo(ByVal uiAction As UInteger, ByVal uiParam As UInteger, ByRef pvParam As Integer, ByVal fWinIni As UInteger) As Integer
End Function

Public Function IsScreenSaverActive() As Boolean
  Dim ScreenSavingEnabled As Integer
  Call SystemParametersInfo(SPI_GETSCREENSAVEACTIVE, 0UI, ScreenSavingEnabled, SPIF_SENDWININICHANGE)
  IsScreenSaverActive = Not (ScreenSavingEnabled = 0)
End Function

private const uint SPI_GETSCREENSAVEACTIVE = 16U;
private const uint SPIF_SENDWININICHANGE = 2U;

[System.Runtime.InteropServices.DllImport("user32.dll")]
private static extern int SystemParametersInfo(uint uiAction, uint uiParam, ref int pvParam, uint fWinIni);

public static bool IsScreenSaverActive() {
  int ScreenSavingEnabled = 0;
  SystemParametersInfo(SPI_GETSCREENSAVEACTIVE, 0U, ref ScreenSavingEnabled, SPIF_SENDWININICHANGE);
  return ScreenSavingEnabled != 0;
}