code: function attach(ent) {
          ent._drawContext = this.context;
          // attach the entity's div element to the dom layer
          this._div.appendChild(ent._element);
          // set position style and entity id
          ent._element.style.position = "absolute";
          ent._element.id = "ent" + ent[0];
      }
docs: @
  #.attach
  @comp DomLayer
  @kind Method
  @private
  
  @sign public .attach(ent)
  @param ent - The entity to add
  
  Add an entity to the layer