RMC_SetHelpingGrid function.
Set raster size and line color of a helping grid
Syntax
	nResult (LONG) = RMC_SetHelpingGrid( ByVal nCtrlId (LONG), ByVal nSize (LONG), Optional ByVal nGridColor (LONG) )
Parameter
	nCtrlId (LONG)
		Unique ID of the chart control.
	nSize (LONG)
		Raster size of the grid in pixel. If 0, no grid gets painted.
	nGridColor (LONG)
		Color of the grid lines as a Color... constant. If omitted or 0: Gray.
Return value
	0
		No error, function succeeded.
	RMC_ERROR_CTRLID
		Wrong control ID (0 or no chart with this control ID was found).
Remarks
		The helping grid covers always the whole chart and gets painted at last. It's useful in design mode, especially when adding CustomObjects to your chart.