Callbacks, can we keep them??

[arthurhjorth]

As we all learned when @LaCuneta wrote his response here, https://stackoverflow.com/questions/54332081/netlogo-levelspace-how-to-pass-strings-between-two-child-models, callbacks are currently possible in LevelSpace.

My use case is LevelSpace child models acting as input to each other. I've made a child model that allows kids to use their mouse to draw a graph. This graph is then returned to the parent model who can then use it as model input (@cbradyatinquire you might like this, so tagging you :) ). I can make it work without a callback, but from a user experience perspective, a callback makes it so much nicer.

I know we've talked about this many times, and I know there are potential pitfalls. For modeling purposes, they also break with some Netlogo language convetions. But they are SOOOOOO nice to have for these more advanced use cases with LevelSpace. Can we keep them, @qiemem ? What, if anything, would we need to do to make sure that they don't break a model?

[arthurhjorth]

duplicate of #133