As per title, can you please add one and also pass back all the parent values that have actually changed? I always need to run some code when the parent ID changes, previously I was extending _afterSave() in my own module, but I noticed that it didn't work when I re-order the nodes in the tree by dragging them.

Right now we have an _afterSave() function we can extend/overload when saving a node in ACP, however, there is no way to extend the reorder() function unless we extend it first and copy/paste almost the same code. My goal was to add my own code AFTER the function runs but I can't because there is a redirect/sendOutput at the end of it.

I have worked around this limitation in my own code (copy/pasting the whole function), but it would be nice to see this supported in the core code. That way I don't need to check in each version if anything was changed in the function in order to update my copy/paste function.

Makes sense - I'll see about getting it added for 4.1.17.