Make a custom editor for obj or objects.

By default an appropriate editor is chosen that has a matching CustomEditor attribute. If an editorType is specified, an editor of that type is created instead. Returns NULL if obj doesn't have a custom editor class defined.

Consider a script WaypointPathEditor for editing the Transforms of a wayPoint array.

import System.Linq;
@CustomEditor (WaypointPath)
class WaypointPathEditor extends Editor {
	
	var currentTransformEditor;
	var waypoints : Transform[];
	var selectedTransform :Transform;
	var optionsList : String[];
	var index = 0;
	var myWayPath : WaypointPath; 
	function GetWaypoints () {
    	var myWayPath = target as WaypointPath;
		
        // Gets only the valid objects from WaypointPath
		if (myWayPath.wayPointArray != null) {
			waypoints = myWayPath.wayPointArray.Where (function(obj) { return obj != null; }).ToArray ();
			optionsList = waypoints.Select (function(obj, index){index.ToString () + ". " + obj.name;}).ToArray ();	
			}
		
      		
	}
	
	function OnInspectorGUI () {
    	GetWaypoints ();
        DrawDefaultInspector ();
        EditorGUILayout.Space ();
        EditorGUI.BeginChangeCheck ();
		
		if (optionsList != null)
        	index = EditorGUILayout.Popup ("Select Waypoint", index, optionsList);
		
		if (EditorGUI.EndChangeCheck ()) {
			var tmpEditor;
			if (index < waypoints.Length) {
				selectedTransform = waypoints[index];
                //Creates an Editor for selected Component from a Popup
				tmpEditor = Editor.CreateEditor (selectedTransform);
			}else {
			
 				selectedTransform = null;
			}
			
 			// If there isn't a Transform currently selected then destroy the existing editor
			if (currentTransformEditor != null) {
				DestroyImmediate (currentTransformEditor);
			}
			
			currentTransformEditor = tmpEditor;
		}
	    //Shows the created Editor beneath CustomEditor
		if (currentTransformEditor != null && selectedTransform != null) {
			currentTransformEditor.OnInspectorGUI ();
		}
    }
}

And the script attached to a waypath GameObject:

//WaypointPath.js
// This is not an editor script.
var wayPointArray : Transform[];