Spline Editor: Maintain object selection and object attachments

Hi.

I'm working on a spline editor within the Unity editor. Currently I am able to add/delete points, move them around etc. However, I'd like to add this functionality:

User drags GameObject (in scene) to spline object (in scene) and this object will attach itself to the spline. Technically, the editor script will detect the object being dragged to the spline and add it. This will add a PathedObject component to object allowing the user to move the object around the spline visually (it'll have a slider or something).

However, I have some issues:

1. How do you maintain selection of an object in scene view while dragging another?

2. How do you detect "collision" or perhaps even an object being dragged and dropped onto another?

Are these two items even possible from within an editor?

I tried using EditorGUILayout.ObjectField to add objects to the spline, however, it appears to currently not support selecting objects in the scene view, only library objects.

The other potential work-around could be just adding the objects to the spline object as children, however, I don't think there is an event for this and I'd like to be able to add components to spline objects as they are added.