private void assignBoxPartListener() {
	final IPartService partService = getSite().getWorkbenchWindow().getPartService();
	if (partService == null) { return; }
	if (partListeners == null) {
		partListeners = new HashMap<>();
	}
	final IPartListener2 oldListener = partListeners.get(partService);
	if (oldListener == null) {
		final IPartListener2 listener = new BoxDecoratorPartListener();
		partService.addPartListener(listener);
		partListeners.put(partService, listener);
	}
}
 

public void removeListener(IPartListener2 listener) {
	IWorkbenchPage page = EmacsPlusUtils.getWorkbenchPage(); 
	if (page != null && location != null) {
		page.removePartListener(listener);
	}
	location.clearListener();
	location = null;
}
 

public void addListener(IPartListener2 listener) {
	IWorkbenchPage page = EmacsPlusUtils.getWorkbenchPage(); 
	if (page != null) {
		page.addPartListener(listener);
	}
}
 

public SafePartListener2(Logger log, IPartListener2 toForwardTo) {
  this.toForwardTo = toForwardTo;
  this.log = log;
}