// Calculate the marque zoom rectangle to zoom.
CompoundModel root = (CompoundModel)
((ChsRootEditPart)this.main.getViewer().getRootEditPart().
getChildren().get(0)).getModel();
Rectangle r = root.calculateBounds();
// Graph Margins are added
r.expand(LGraph.getGraphMargin(), LGraph.getGraphMargin());
// Zoom to rectangle to fit in window