public void createDifference() {
try {
Workflow workflow = this.engine.getWorkflow();
MonitorEventData eventData = this.engine.getMonitor()
.getEventData();
WorkflowModifier modifier = new WorkflowModifier(workflow,
eventData);
Workflow diffWorkflow = modifier.createDifference();
GraphCanvas canvas = this.engine.getGUI().newGraphCanvas(true);
canvas.setWorkflow(diffWorkflow);
} catch (MonitorException e) {
this.engine.getErrorWindow().error(e);
} catch (GraphException e) {