MarkerHorizontal Class
The MarkerHorizontal class represents a HORIZONTAL marker on a graph. It can be used to customize horizontal marker style and options.
Some attributes can be read and changed with get and set :
datalock: Whether the marker value will be restrained to data range.labelside: The label side (ABOVE/BELOW).linecolor: The marker line color.linestyle: The marker line style (SOLID, DOTTED, DASHED).linewidth: The marker line width.value: The Y position of the marker line (a dataset y value).xlabelposition: The X position of the marker text (a dataset x value).