diff --git a/h/static/scripts/annotator/main.js b/h/static/scripts/annotator/main.js
@@ -8,7 +8,8 @@ require('jquery-scrollintoview')
 var g = Annotator.Util.getGlobal();
 if (g.wgxpath) g.wgxpath.install();

-require('node-iterator-shim').install();
+var nodeIteratorShim = require('node-iterator-shim')
+nodeIteratorShim();

 // Applications
 Annotator.Guest = require('./guest')
diff --git a/h/static/scripts/annotator/plugin/bucket-bar.coffee b/h/static/scripts/annotator/plugin/bucket-bar.coffee
@@ -5,6 +5,9 @@ $ = Annotator.$


 # Get the bounding client rectangle of a collection in viewport coordinates.
+# Unfortunately, Chrome has issues[1] with Range.getBoundingClient rect or we
+# could just use that.
+# [1] https://code.google.com/p/chromium/issues/detail?id=324437
 getBoundingClientRect = (collection) ->
  # Reduce the client rectangles of the highlights to a bounding box
  rects = collection.map((n) -> n.getBoundingClientRect())
@@ -16,11 +19,14 @@ getBoundingClientRect = (collection) ->


 # Scroll to the next closest anchor off screen in the given direction.
-scrollToClosest = (objs, direction) ->
+scrollToClosest = (anchors, direction) ->
  dir = if direction is "up" then +1 else -1
-  {next} = objs.reduce (acc, obj) ->
+  {next} = anchors.reduce (acc, anchor) ->
+    unless anchor.highlights?.length
+      return acc
+
    {start, next} = acc
-    rect = getBoundingClientRect(obj.highlights)
+    rect = getBoundingClientRect(anchor.highlights)

    # Ignore if it's not in the right direction.
    if (dir is 1 and rect.top >= 0)
@@ -31,10 +37,10 @@ scrollToClosest = (objs, direction) ->
    # Select the closest to carry forward
    if not next?
      start: rect.top
-      next: obj
+      next: anchor
    else if start * dir < rect.top * dir
      start: rect.top
-      next: obj
+      next: anchor
    else
        acc
  , {}
@@ -81,23 +87,25 @@ class Annotator.Plugin.BucketBar extends Annotator.Plugin
      $(element).append @element

  pluginInit: ->
+    _update = => this.update()
+
    events = [
      'annotationCreated', 'annotationUpdated', 'annotationDeleted',
      'annotationsLoaded'
    ]
    for event in events
-      @annotator.subscribe event, this._scheduleUpdate
+      @annotator.subscribe event, _update

-    $(window).on 'resize scroll', this._scheduleUpdate
+    $(window).on 'resize scroll', _update

    for scrollable in @options.scrollables ? []
-      $(scrollable).on 'resize scroll', this._scheduleUpdate
+      $(scrollable).on 'resize scroll', _update

  destroy: ->
-    $(window).off 'resize scroll', this._scheduleUpdate
+    $(window).off 'resize scroll', _update

    for scrollable in @options.scrollables ? []
-      $(scrollable).off 'resize scroll', this._scheduleUpdate
+      $(scrollable).off 'resize scroll', _update

  _collate: (a, b) ->
    for i in [0..a.length-1]
@@ -109,38 +117,32 @@ class Annotator.Plugin.BucketBar extends Annotator.Plugin

  # Update sometime soon
  update: ->
-    this._scheduleUpdate()
-
-  _scheduleUpdate: =>
    return if @_updatePending?
    @_updatePending = raf =>
      delete @_updatePending
      @_update()

-
-  _update: =>
+  _update: ->
    # Keep track of buckets of annotations above and below the viewport
    above = []
    below = []

    # Construct indicator points
-    points = @annotator.anchored.reduce (points, obj, i) =>
-      hl = obj.highlights
-
-      if hl.length is 0
+    points = @annotator.anchors.reduce (points, anchor, i) =>
+      unless anchor.highlights?.length
        return points

-      rect = getBoundingClientRect(hl)
+      rect = getBoundingClientRect(anchor.highlights)
      x = rect.top
      h = rect.bottom - rect.top

      if x < 0
-        if obj not in above then above.push obj
+        if anchor not in above then above.push anchor
      else if x + h > window.innerHeight
-        if obj not in below then below.push obj
+        if anchor not in below then below.push anchor
      else
-        points.push [x, 1, obj]
-        points.push [x + h, -1, obj]
+        points.push [x, 1, anchor]
+        points.push [x + h, -1, anchor]
      points
    , []

@@ -166,23 +168,23 @@ class Annotator.Plugin.BucketBar extends Annotator.Plugin
    .sort(this._collate)
    .reduce ({buckets, index, carry}, [x, d, a], i, points) =>
      if d > 0                                            # Add annotation
-        if (j = carry.objs.indexOf a) < 0
-          carry.objs.unshift a
+        if (j = carry.anchors.indexOf a) < 0
+          carry.anchors.unshift a
          carry.counts.unshift 1
        else
          carry.counts[j]++
      else                                                # Remove annotation
-        j = carry.objs.indexOf a                          # XXX: assert(i >= 0)
+        j = carry.anchors.indexOf a                       # XXX: assert(i >= 0)
        if --carry.counts[j] is 0
-          carry.objs.splice j, 1
+          carry.anchors.splice j, 1
          carry.counts.splice j, 1

      if (
        (index.length is 0 or i is points.length - 1) or  # First or last?
-        carry.objs.length is 0 or                         # A zero marker?
+        carry.anchors.length is 0 or                      # A zero marker?
        x - index[index.length-1] > @options.gapSize      # A large gap?
      )                                                   # Mark a new bucket.
-        buckets.push carry.objs.slice()
+        buckets.push carry.anchors.slice()
        index.push x
      else
        # Merge the previous bucket, making sure its predecessor contains
@@ -195,15 +197,15 @@ class Annotator.Plugin.BucketBar extends Annotator.Plugin
        else
          last = buckets[buckets.length-1]
          toMerge = []
-        last.push a0 for a0 in carry.objs when a0 not in last
+        last.push a0 for a0 in carry.anchors when a0 not in last
        last.push a0 for a0 in toMerge when a0 not in last

      {buckets, index, carry}
    ,
      buckets: []
      index: []
      carry:
-        objs: []
+        anchors: []
        counts: []
        latest: 0

@@ -242,19 +244,19 @@ class Annotator.Plugin.BucketBar extends Annotator.Plugin

      div.addClass('annotator-bucket-indicator')

-      # Creates highlights corresponding bucket when mouse is hovered
+      # Focus corresponding highlights bucket when mouse is hovered
      # TODO: This should use event delegation on the container.
      .on 'mousemove', (event) =>
        bucket = @tabs.index(event.currentTarget)
-        for obj in @annotator.anchored
-          toggle = obj in @buckets[bucket]
-          $(obj.highlights).toggleClass('annotator-hl-focused', toggle)
+        for anchor in @annotator.anchors
+          toggle = anchor in @buckets[bucket]
+          $(anchor.highlights).toggleClass('annotator-hl-focused', toggle)

      # Gets rid of them after
      .on 'mouseout', (event) =>
        bucket = @tabs.index(event.currentTarget)
-        for obj in @buckets[bucket]
-          $(obj.highlights).removeClass('annotator-hl-focused')
+        for anchor in @buckets[bucket]
+          $(anchor.highlights).removeClass('annotator-hl-focused')

      # Does one of a few things when a tab is clicked depending on type
      .on 'click', (event) =>
@@ -268,7 +270,7 @@ class Annotator.Plugin.BucketBar extends Annotator.Plugin
        else if (@isLower bucket)
          scrollToClosest(@buckets[bucket], 'down')
        else
-          annotations = (obj.annotation for obj in @buckets[bucket])
+          annotations = (anchor.annotation for anchor in @buckets[bucket])
          annotator.selectAnnotations annotations,
            (event.ctrlKey or event.metaKey),

diff --git a/h/static/scripts/annotator/plugin/pdf.coffee b/h/static/scripts/annotator/plugin/pdf.coffee
@@ -1,16 +1,17 @@
-raf = require('raf')
-Promise = require('es6-promise').Promise
+Promise = global.Promise ? require('es6-promise').Promise
 Annotator = require('annotator')

-highlighter = require('../highlighter')
-

 class PDF extends Annotator.Plugin
-  documentPromise: null
+  documentLoaded: null
+  observer: null
+  pdfViewer: null
+  updatePromise: null
+  updateTimeout: null

  pluginInit: ->
-    viewer = PDFViewerApplication.pdfViewer.viewer
-    viewer.classList.add('has-transparent-text-layer')
+    @pdfViewer = PDFViewerApplication.pdfViewer
+    @pdfViewer.viewer.classList.add('has-transparent-text-layer')

    if PDFViewerApplication.loading
      @documentLoaded = new Promise (resolve) ->
@@ -21,10 +22,17 @@ class PDF extends Annotator.Plugin
    else
      @documentLoaded = Promise.resolve()

-    document.addEventListener('pagerendered', @onpagerendered)
+    @observer = new MutationObserver((mutations) => this.update())
+    @observer.observe(@pdfViewer.viewer, {
+      attributes: true
+      attributeFilter: ['data-loaded']
+      childList: true
+      subtree: true
+    })

  destroy: ->
-    document.removeEventListener('pagerendered', @onpagerendered)
+    @pdfViewer.viewer.classList.remove('has-transparent-text-layer')
+    @observer.disconnect()

  uri: ->
    @documentLoaded.then ->
@@ -50,42 +58,51 @@ class PDF extends Annotator.Plugin

      return {title, link}

-  onpagerendered: (event) =>
-    annotator = {anchored, unanchored} = @annotator
-    page = PDFViewerApplication.pdfViewer.pages[event.detail.pageNumber - 1]
-
-    waitForTextLayer = ->
-      unless (page.textLayer.renderingDone)
-        return new Promise(raf).then(waitForTextLayer)
-
-    reanchor = ->
-      unanchored = unanchored.splice(0, unanchored.length)
-
-      placeholder = page.el.getElementsByClassName('annotator-placeholder')[0]
-      if placeholder?
-        unchanged = []
-        for info in anchored
-          attempt = false
-
-          for hl in info.highlights
-            if placeholder.contains(hl)
-              attempt = true
-              break
-
-          if attempt
-            highlighter.removeHighlights(info.highlights)
-            delete info.highlights
-            unanchored.push(info)
-          else
-            unchanged.push(info)
-
-        anchored.splice(0, anchored.length, unchanged...)
-        page.el.removeChild(placeholder)
-
-      for obj in unanchored
-        annotator.setupAnnotation(obj.annotation)
-
-    waitForTextLayer().then(reanchor)
+  update: ->
+    self = this
+    {annotator, pdfViewer} = this
+
+    _throttle = ->
+      if self.updateTimeout?
+        clearTimeout(self.updateTimeout)
+      self.updateTimeout = setTimeout(_update, 200)
+
+    _update = ->
+      anchors = []
+      annotations = []
+
+      for page in pdfViewer.pages when page.textLayer?.renderingDone
+        div = page.div ? page.el
+        placeholder = div.getElementsByClassName('annotator-placeholder')[0]
+
+        switch page.renderingState
+          when RenderingStates.INITIAL
+            page.textLayer = null
+          when RenderingStates.FINISHED
+            if placeholder?
+              placeholder.parentNode.removeChild(placeholder)
+
+      for anchor in annotator.anchors when anchor.annotation not in annotations
+        unless anchor.range? and anchor.highlights?
+          delete anchor.range
+          annotations.push(anchor.annotation)
+          continue
+
+        for hl in anchor.highlights
+          if not document.body.contains(hl)
+            delete anchor.range
+            annotations.push(anchor.annotation)
+            break
+
+      for annotation in annotations
+        annotator.setupAnnotation(annotation)
+        anchors.push(annotation.anchors)
+
+      self.updateTimeout = null
+      self.updatePromise = Promise.all(anchors)
+
+    @annotator.plugins.BucketBar?.update()
+    Promise.resolve(@updatePromise).then(_throttle)

 Annotator.Plugin.PDF = PDF

diff --git a/h/static/scripts/annotator/test/guest-test.coffee b/h/static/scripts/annotator/test/guest-test.coffee
@@ -1,4 +1,4 @@
-Promise = require('es6-promise').Promise
+Promise = global.Promise ? require('es6-promise').Promise
 Annotator = require('annotator')
 Guest = require('../guest')

diff --git a/h/static/scripts/test/annotation-mapper-test.coffee b/h/static/scripts/test/annotation-mapper-test.coffee
@@ -1,4 +1,4 @@
-Promise = require('es6-promise').Promise
+Promise = global.Promise ? require('es6-promise').Promise
 {module, inject} = require('angular-mock')

 assert = chai.assert
diff --git a/h/static/scripts/vendor/diff_match_patch_uncompressed.js b/h/static/scripts/vendor/diff_match_patch_uncompressed.js
diff --git a/h/static/scripts/vendor/dom_text_matcher.js b/h/static/scripts/vendor/dom_text_matcher.js
diff --git a/h/static/scripts/vendor/text_match_engines.js b/h/static/scripts/vendor/text_match_engines.js
diff --git a/h/static/styles/inject.scss b/h/static/styles/inject.scss
@@ -135,7 +135,10 @@ $base-font-size: 14px;
 }

 .annotator-placeholder {
+  opacity: 0;
  position: absolute;
+  top: 50%;
+  z-index: -1;
 }


diff --git a/package.json b/package.json
@@ -9,11 +9,12 @@
    "clean-css": "2.2.2",
    "coffee-script": "1.7.1",
    "coffeeify": "^1.0.0",
+    "diff-match-patch": "^1.0.0",
    "dom-seek": "^1.0.0-beta.1",
    "es6-promise": "^2.1.0",
    "extend": "^2.0.0",
    "hammerjs": "^2.0.4",
-    "node-iterator-shim": "^1.0.0-beta.1",
+    "node-iterator-shim": "^1.0.0-beta.3",
    "node-uuid": "^1.4.3",
    "raf": "^2.0.4",
    "strip-bomify": "^0.1.0",
@@ -56,14 +57,12 @@
    "annotator-auth": "./h/static/scripts/vendor/annotator.auth.js",
    "angular": "./h/static/scripts/vendor/angular.js",
    "angular-mock": "./h/static/scripts/vendor/angular-mocks.js",
-    "diff-match-patch": "./h/static/scripts/vendor/diff_match_patch_uncompressed.js",
-    "dom-text-matcher": "./h/static/scripts/vendor/dom_text_matcher.js",
    "es6-promise": "./node_modules/es6-promise/dist/es6-promise.js",
    "hammerjs": "./node_modules/hammerjs/hammer.js",
    "jquery": "./h/static/scripts/vendor/jquery.js",
    "jquery-scrollintoview": "./h/static/scripts/vendor/jquery.scrollintoview.js",
    "jschannel": "./h/static/scripts/vendor/jschannel.js",
-    "text-match-engines": "./h/static/scripts/vendor/text_match_engines.js"
+    "node-iterator-shim": "./node_modules/node-iterator-shim/dist/node-iterator-shim.js"
  },
  "browserify-shim": {
    "annotator": {
@@ -85,8 +84,6 @@
      ]
    },
    "angular-mock": "global:angular.mock",
-    "diff-match-patch": "diff_match_patch",
-    "dom-text-matcher": "DomTextMatcher",
    "es6-promise": "ES6Promise",
    "hammerjs": "Hammer",
    "jquery": "$",
@@ -96,6 +93,6 @@
      ]
    },
    "jschannel": "Channel",
-    "text-match-engines": "TextMatchEngines"
+    "node-iterator-shim": "nodeIteratorShim"
  }
 }