I can get the 'workarea' of the primary monitor using:
Func _GetDesktopArea()
Local Const $SPI_GETWORKAREA = 48
Local $tWorkArea = DllStructCreate($tagRECT)
_WinAPI_SystemParametersInfo($SPI_GETWORKAREA, 0, DllStructGetPtr($tWorkArea))
Local $aReturn[4] = [DllStructGetData($tWorkArea, "Left"), DllStructGetData($tWorkArea, "Top"), _
DllStructGetData($tWorkArea, "Right") - DllStructGetData($tWorkArea, "Left"), DllStructGetData($tWorkArea, "Bottom") - DllStructGetData($tWorkArea