Problem with LS models being edited in tabs while also edited in real NetLogo instance

This is borderline user-issue, and not really a code issue. But given that we want the IDE-part of LS to be good, I still think this is something we should consider:

I was working on a model this morning and had to create a LS child model. I realized pretty quickly that I had to edit the interface of the child model, and I therefore had to open it in a full-fledged NetLogo instance, so that's what I did.

I worked on the child model for a while in a separate instance, closed it down, and then shut down the NetLogo instance with the main model in it, which ALSO contained the child model in a separate tab.

I didn't think too much about it when NetLogo asked me if I wanted to save changes to the model, because I thought it was asking me about the main model. Unfortunately it meant the child model, and all the work I had done on it in the other instance was overwritten.

I am not totally sure how we should handle this, but the easiest way is to make very clear that saving a model will also save the child model, or to pop up a special "HEY USER, PAY ATTENTION!!!!" message when it tries to save a LevelSpace model.

Alternatively we could check if there is a .tmp file that has been saved more recently than the one that LevelSpace child-tab. I can see all kinds of horrible issues with this solution, but I also like it.

No files, tests, or entry points are named. First clarify the intended behavior for saving a LevelSpace model when a child model was edited elsewhere, then identify the save and child-tab handling code; done means an agreed behavior prevents accidental overwrites and is covered by a reproducible test.