Closing as won't fix: the problem is the "Bound to layout" behavior does its clamping after the events run, so it works in this order:
1. drag-and-drop moves object outside layout
2. event fires and spawns object
3. bound-to-layout moves object back inside layout
Changing this order will doubtless break other projects that depend on things working this way, so we can't really change it. It should be straightforwards to work around if you just do the layout bounding in events instead of with the behavior.