When we unpickle the plot manager, we walk our way through the tree, calling plotPanel.addPlot(...) and plotPanel.addSeries(...) as we go. In this case, plotPanel is a class that is a wx.Frame (well, an MDI frame in our case) that has a mpl figure on it, and various methods that know how to manipulate the data from our Plot and Series objects to create appropriate mpl analogues. This is strictly