Methods for charts with axes.

$graph->set_x_label_font(font specification)
$graph->set_y_label_font(font specification)
$graph->set_x_axis_font(font specification)
$graph->set_y_axis_font(font specification)
$graph->set_values_font(font specification)

    Set the font for the x and y axis label, the x and y axis value labels, and for the values printed above the data points. See "FONTS".