     tiles = @tile_provider.get_tiles_by_extent(extent, zoom_level)
 
     parents = []
-    create_us = []
+    need_load = []
     cached = []
 
     for t in tiles

        else
          @_create_tile(cx, cy, cz, cbounds, true)

  _update: () =>

    if window.stop?
      window.stop()

    @_draw_tile(tile_key)
    @map_canvas.restore()

  _render_tiles: (tile_keys) ->
    @map_canvas.save()
    @map_canvas.rect(
