SetIndexStyle - MQL4 Documentation

void SetIndexStyle(

int index, int type, int style=EMPTY, int width=EMPTY, color clr=CLR_NONE)

Sets the new type, style, width and color for a given indicator line.

Parameters:

index	-	Line index. Must lie between 0 and 7.
type	-	Shape style. Can be one of Drawing shape styles listed.
style	-	Drawing style. It is used for one-pixel thick lines. It can be one of the Drawing shape styles listed. EMPTY value means that the style will not be changed.
width	-	Line width. Valid values are: 1,2,3,4,5. EMPTY value means that width will not be changed.
clr	-	Line color. Absence of this parameter means that the color will not be changed.

Sample:

  SetIndexStyle(3, DRAW_LINE, EMPTY, 2, Red);