public void setBpmnDiagram(final BPMNDiagram bpmnDiagram) {
		// do we need to create a new Diagram or is this already in the Graphiti model?
		Diagram oldDiagram = null;
		Diagram diagram = null;
		final Resource resource = getDiagramTypeProvider().getDiagram().eResource();
		for (EObject o : resource.getContents()) {
			if (o instanceof Diagram) {
				Diagram d = (Diagram)o;
				EObject bo = Graphiti.getLinkService().getBusinessObjectForLinkedPictogramElement(d);
				if (bo == bpmnDiagram) {
					oldDiagram = d;
					break;
				}
			}
		}
		
		if (oldDiagram==null) {
			// create a new one
			String typeId = getDiagramTypeProvider().getDiagram().getDiagramTypeId();
			final Diagram newDiagram = Graphiti.getCreateService().createDiagram(typeId, bpmnDiagram.getName(), true);
			final IFeatureProvider featureProvider = getDiagramTypeProvider().getFeatureProvider();
			TransactionalEditingDomain domain = getEditingDomain();
			domain.getCommandStack().execute(new RecordingCommand(domain) {
				protected void doExecute() {
					resource.getContents().add(newDiagram);
					newDiagram.setActive(true);
					featureProvider.link(newDiagram, bpmnDiagram);
				}
			});
			diagram = newDiagram;
		}
		else {
			// already there
			diagram = oldDiagram;
		}
		
		// set the new Diagram in the DTP and refresh graphical viewer
		getDiagramTypeProvider().init(diagram, this);
		refreshContent();
		// remember this for later
		this.bpmnDiagram = bpmnDiagram;
	}