Is there a way for case objects to have cases share fields?

[treeform]

I also tried nkDocument, nkCanvas, but I need nkCanvas to eventually be 
different from document?
    
    
      Node = ref object
        id: string
        name: string
        case kind: NodeKind
        of nkDocument, nkCanvas:
          children: seq[Node]
        of nkCanvas:
          backgroundColorColor: Color
          prototypeStartNodeID: string
        of nkRectangle:
          box: Rect
    
    
    Run