how to lock vuedraggable for specific array nested level

[asmarcin]

Hi,
i need advice how to achieve

Code: https://github.com/SortableJS/vue.draggable.next/blob/master/example/components/nested/nested-test.vue

Step by step scenario

i want to enable dragging for only first first level nested elements (i did it with class)

i want to lock dragging elements to top level of array, dragged element should be dropped only inside parent (another element from top level of array)

    elements: [ //top level, i dont want to allow drop here
      {
        id: 1,
        name: "Shrek",
        elements: [] //here should be possible to drop
      },
      {
        id: 2,
        name: "Fiona",
        elements: [ //elements from here should be draggable (i did it with class)
          { 
            id: 4,
            name: "Lord Farquad",
            elements: []
          },
          {
            id: 5,
            name: "Prince Charming",
            elements: []
          }
        ]
      },
      {
        id: 3,
        name: "Donkey",
        elements: [] //here should be possible to drop
      }
    ]
  }

Actual Solution

when im dragging element under element from top level of array its ok, then related context is array from top level, but when i want to drag element in the same row as top level element (should be not allowed) related context is also element from level 1, i tried do some copmaring in :on-move, but its called a lot of times and performance is dying

Expected Solution

allow drop elements only under elements from top level of array, lock dragging element to top level of array