I guess you want your XML file to reflect the current spatialization
of your graph.
To do that, you have to probably set the attributes @x and @y of each
of your nodes according to their visual node views x and y
coordinates, before saving your xml file.
Thus, if you reload your graph, you would be able to use
directPlacementLayouter which use xml attributes to draw nodes (if
such attributes exist).
DjiAntika.