constants GridLinesStyleEnum
The GridLinesStyle type specifies the style to show the control's grid lines. The GridLineStyle property indicates the style of the gridlines being displayed in the view if the DrawGridLines property is not zero. The GridLinesStyle enumeration specifies the style for horizontal or/and vertical gridlines in the control. The DrawGridLines property of the Chart object specifies whether the grid lines are shown in the chart part of the control.

NameValueDescription
exGridLinesDot0 The control's gridlines are shown as dotted.
exGridLinesHDot41 The horizontal control's gridlines are shown as dotted.
exGridLinesVDot42 The vertical control's gridlines are shown as dotted.
exGridLinesDot43 The control's gridlines are shown as solid.
exGridLinesHDash4 The horizontal control's gridlines are shown as dashed.
exGridLinesVDash8 The vertical control's gridlines are shown as dashed.
exGridLinesDash12 The control's gridlines are shown as dashed.
exGridLinesHSolid16 The horizontal control's gridlines are shown as solid.
exGridLinesVSolid32 The vertical control's gridlines are shown as solid.
exGridLinesSolid48 The control's gridlines are shown as solid.
exGridLinesBehind256 The control's vertical gridlines are shown behind bars. This option has effect for the chart area only, so it has to be used by Chart.GridLineStyle property. For instance, Chart.GridLineStyle = GridLinesStyleEnum.exGridLinesHSolid Or GridLinesStyleEnum.exGridLinesBehind shows horizontal gridlines as solid, and the vertical gridlines shows behind the bars. 
exGridLinesGeometric512 The control's gridlines are drawn using a geometric pen. The exGridLinesGeometric flag can be combined with any other flag. A geometric pen can have any width and can have any of the attributes of a brush, such as dithers and patterns. A cosmetic pen can only be a single pixel wide and must be a solid color, but cosmetic pens are generally faster than geometric pens. The width of a geometric pen is always specified in world units. The width of a cosmetic pen is always 1.