Sub UpdateSystemActivity()
  
  #if TargetCarbon
    declare function myUpdateSystemActivity lib "Carbon" alias "UpdateSystemActivity" (activity as Integer) as short
    
    const OverallAct                    = 0 // Delays idle sleep by small amount                 */
    const UsrActivity                   = 1 // Delays idle sleep and dimming by timeout time          */
    const NetActivity                   = 2 // Delays idle sleep and power cycling by small amount         */
    const HDActivity                    = 3 // Delays hard drive spindown and idle sleep by small amount  */
    const IdleActivity                  = 4 // Delays idle sleep by timeout time                 */
    
    dim e as Integer
    
    e=myUpdateSystemActivity(UsrActivity)
    
    // you may react on an error if e is not 0 after the call.
    
  #endif
End Sub