public boolean onButtonPressed() { CompoundCommand command = new CompoundCommand(IBPELUIConstants.CMD_ADD_EVENTHANDLER); final EventHandler eventHandler = BPELFactory.eINSTANCE.createEventHandler(); // Create an empty OnEvent inside it. final OnEvent onEvent = (OnEvent) UIObjectFactoryProvider.getInstance() .getFactoryFor(BPELPackage.eINSTANCE.getOnEvent()) .createInstance(); eventHandler.getEvents().add(onEvent); command.add(new InsertInContainerCommand((EObject) modelObject, eventHandler, null)); command.add(new SetNameAndDirectEditCommand(onEvent, viewer)); ModelHelper.getBPELEditor(modelObject).getCommandStack().execute(command); BPELUtil.setShowEventHandler(editPart, true); return true; }