Detecting drag'n'drop without target

I have a working drag’n’drop system, but I can’t find a non-hackish way to detect that a drag’n’drop simply didn’t find any target.

My use case is simple: if I drag a source component over any component that is NOT interested in my source component, I want to do a “detach source component” kind of behavior.
I thought about using dragOperationEnded, but it is called regardless of the success of the operation.