Ok, I've been trying to figure this out on my own, but nothing I do really seems right, and I still don't have it working perfectly anyway, so I'm asking for advice. I've got a document-based, core-data app that makes heavy use of bindings. The Core-Data model is not particularly complicated, but it's not dead simple either. There are 5 entities in it, and they each have a fair number of attributes along with optional relationships to others in the model. Each document contains an array of one of these entities (which by relationship means there are multiple instances of some other types of entities). One type of entity is only supposed to be instantiated once per document. I want an inspector panel that lets one view and modify the attribute values of this entity that's only instantiated once. As there should only be one inspector panel in the application even with multiple documents open, obviously the inspector panel should be in a separate nib. Here's where I'm running in to trouble. What is the correct architecture for having the Inspector panel connect to the entity that's part of MyDocument? Included in this question is the solution to the problem of making the inspector panel update itself when a different document is brought to the front. The things I'm doing now are overly complicated and don't really work at all. If anyone can explain a good way to do this, I'd really appreciate it. It seems like it has to be a common problem because there are tons of applications with a floating inspector panel which applies to the frontmost document. If anyone can point to a good tutorial that address this rather than explaining it, that would be helpful too. I haven't been able to find one searching myself. I would like something that specifically covers Core Data and Bindings, because I'm using both.