TMultigraph is a collection of TGraph. The number of TGraphs in a TMultigraph is not limited. You can add as many as you want. Therefore the axis of a TMultigraph can be computed only at painting time, and are not defined before that.
TMultigraph is a collection of TGraph. The number of TGraphs in a TMultigraph is not limited. You can add as many as you want. Therefore the axis of a TMultigraph can be computed only at painting time, and are not defined before that.