     @lineDecorationsByScreenRow = {}
     @lineNumberDecorationsByScreenRow = {}
     @customGutterDecorationsByGutterName = {}
-    @blockDecorationsDimensions = new Map
+    @blockDecorationsDimensionsById = new Map
     @screenRowsToMeasure = []
     @transferMeasurementsToModel()
     @transferMeasurementsFromModel()

    @lineHeight * @model.getScreenLineCount()

  getBlockDecorationsHeight: ->
    sizes = Array.from(@blockDecorationsDimensions.values())
    sum = (a, b) -> a + b
    height = sizes.map((size) -> size.height).reduce(sum, 0)
    height

    for decoration in @model.getDecorations(type: "block")
      blockDecorations[decoration.id] = decoration

    @blockDecorationsDimensionsById.forEach (value, key) =>
      unless blockDecorations.hasOwnProperty(key)
        @blockDecorationsDimensionsById.delete(key)

    @shouldUpdateVerticalScrollState = true

