diff --git a/core/blockly.js b/core/blockly.js
index c56224ba3..30de3b1cb 100644
--- a/core/blockly.js
+++ b/core/blockly.js
@@ -122,7 +122,7 @@ Blockly.EventData;
 
 /**
  * Returns the dimensions of the specified SVG image.
- * @param {!Element} svg SVG image.
+ * @param {!SVGElement} svg SVG image.
  * @return {!Object} Contains width and height properties.
  */
 Blockly.svgSize = function(svg) {
@@ -177,11 +177,11 @@ Blockly.svgResize = function(workspace) {
  * Handle a key-down on SVG drawing surface. Does nothing if the main workspace
  * is not visible.
  * @param {!Event} e Key down event.
- * @private
+ * @package
  */
 // TODO (https://github.com/google/blockly/issues/1998) handle cases where there
 // are multiple workspaces and non-main workspaces are able to accept input.
-Blockly.onKeyDown_ = function(e) {
+Blockly.onKeyDown = function(e) {
   var mainWorkspace = Blockly.mainWorkspace;
 
   if (Blockly.utils.isTargetInput(e) ||
@@ -343,13 +343,13 @@ Blockly.hideChaff = function(opt_allowToolbox) {
     // For now the trashcan flyout always autocloses because it overlays the
     // trashcan UI (no trashcan to click to close it).
     if (workspace.trashcan &&
-      workspace.trashcan.flyout_) {
-      workspace.trashcan.flyout_.hide();
+      workspace.trashcan.flyout) {
+      workspace.trashcan.flyout.hide();
     }
     var toolbox = workspace.getToolbox();
     if (toolbox &&
-        toolbox.flyout_ &&
-        toolbox.flyout_.autoClose) {
+        toolbox.getFlyout() &&
+        toolbox.getFlyout().autoClose) {
       toolbox.clearSelection();
     }
   }
diff --git a/core/dropdowndiv.js b/core/dropdowndiv.js
index 689d32a3e..68412dbee 100644
--- a/core/dropdowndiv.js
+++ b/core/dropdowndiv.js
@@ -259,11 +259,12 @@ Blockly.DropDownDiv.showPositionedByField = function(field,
  * @private
  */
 Blockly.DropDownDiv.getScaledBboxOfBlock_ = function(block) {
-  var bBox = block.getSvgRoot().getBBox();
+  var blockSvg = block.getSvgRoot();
+  var bBox = blockSvg.getBBox();
   var scale = block.workspace.scale;
   var scaledHeight = bBox.height * scale;
   var scaledWidth = bBox.width * scale;
-  var xy = Blockly.utils.style.getPageOffset(block.getSvgRoot());
+  var xy = Blockly.utils.style.getPageOffset(blockSvg);
   return new Blockly.utils.Rect(
       xy.y, xy.y + scaledHeight, xy.x, xy.x + scaledWidth);
 };
diff --git a/core/flyout_base.js b/core/flyout_base.js
index 35b353e6e..349322715 100644
--- a/core/flyout_base.js
+++ b/core/flyout_base.js
@@ -43,7 +43,8 @@ goog.require('Blockly.Xml');
 
 /**
  * Class for a flyout.
- * @param {!Object} workspaceOptions Dictionary of options for the workspace.
+ * @param {!Blockly.Options} workspaceOptions Dictionary of options for the
+ *     workspace.
  * @constructor
  */
 Blockly.Flyout = function(workspaceOptions) {
@@ -228,15 +229,17 @@ Blockly.Flyout.prototype.createDom = function(tagName) {
   this.svgBackground_ = Blockly.utils.dom.createSvgElement('path',
       {'class': 'blocklyFlyoutBackground'}, this.svgGroup_);
   this.svgGroup_.appendChild(this.workspace_.createDom());
-  this.workspace_.getThemeManager().subscribe(this.svgBackground_, 'flyout', 'fill');
-  this.workspace_.getThemeManager().subscribe(this.svgBackground_, 'flyoutOpacity', 'fill-opacity');
+  this.workspace_.getThemeManager().subscribe(
+      this.svgBackground_, 'flyout', 'fill');
+  this.workspace_.getThemeManager().subscribe(
+      this.svgBackground_, 'flyoutOpacity', 'fill-opacity');
   return this.svgGroup_;
 };
 
 /**
  * Initializes the flyout.
- * @param {!Blockly.Workspace} targetWorkspace The workspace in which to create
- *     new blocks.
+ * @param {!Blockly.WorkspaceSvg} targetWorkspace The workspace in which to
+ *     create new blocks.
  */
 Blockly.Flyout.prototype.init = function(targetWorkspace) {
   this.targetWorkspace_ = targetWorkspace;
@@ -265,7 +268,7 @@ Blockly.Flyout.prototype.init = function(targetWorkspace) {
       this.targetWorkspace_.getGesture.bind(this.targetWorkspace_);
 
   // Get variables from the main workspace rather than the target workspace.
-  this.workspace_.variableMap_ = this.targetWorkspace_.getVariableMap();
+  this.workspace_.setVariableMap(this.targetWorkspace_.getVariableMap());
 
   this.workspace_.createPotentialVariableMap();
 };
@@ -432,7 +435,7 @@ Blockly.Flyout.prototype.hide = function() {
 
 /**
  * Show and populate the flyout.
- * @param {!Array|string} xmlList List of blocks to show.
+ * @param {!Array|!NodeList|string} xmlList List of blocks to show.
  *     Variables and procedures have a custom set of blocks.
  */
 Blockly.Flyout.prototype.show = function(xmlList) {
@@ -575,6 +578,7 @@ Blockly.Flyout.prototype.clearOldBlocks_ = function() {
  * @param {!SVGElement} rect The invisible rectangle under the block that acts
  *     as a mat for that block.
  * @protected
+ * @suppress {deprecated} Suppress deprecated bindEvent_ call.
  */
 Blockly.Flyout.prototype.addBlockListeners_ = function(root, block, rect) {
   this.listeners_.push(Blockly.bindEventWithChecks_(root, 'mousedown', null,
@@ -788,8 +792,8 @@ Blockly.Flyout.prototype.isScrollable = function() {
 
 /**
  * Copy a block from the flyout to the workspace and position it correctly.
- * @param {!Blockly.Block} oldBlock The flyout block to copy.
- * @return {!Blockly.Block} The new block in the main workspace.
+ * @param {!Blockly.BlockSvg} oldBlock The flyout block to copy.
+ * @return {!Blockly.BlockSvg} The new block in the main workspace.
  * @private
  */
 Blockly.Flyout.prototype.placeNewBlock_ = function(oldBlock) {
@@ -807,7 +811,8 @@ Blockly.Flyout.prototype.placeNewBlock_ = function(oldBlock) {
 
   // Using domToBlock instead of domToWorkspace means that the new block will be
   // placed at position (0, 0) in main workspace units.
-  var block = Blockly.Xml.domToBlock(xml, targetWorkspace);
+  var block = /** @type {!Blockly.BlockSvg} */
+      (Blockly.Xml.domToBlock(xml, targetWorkspace));
   var svgRootNew = block.getSvgRoot();
   if (!svgRootNew) {
     throw Error('block is not rendered.');
diff --git a/core/gesture.js b/core/gesture.js
index c8aadf03b..df369b9fe 100644
--- a/core/gesture.js
+++ b/core/gesture.js
@@ -315,6 +315,9 @@ Blockly.Gesture.prototype.updateDragDelta_ = function(currentXY) {
  * @private
  */
 Blockly.Gesture.prototype.updateIsDraggingFromFlyout_ = function() {
+  if (!this.targetBlock_) {
+    return false;
+  }
   if (!this.flyout_.isBlockCreatable_(this.targetBlock_)) {
     return false;
   }
@@ -621,7 +624,7 @@ Blockly.Gesture.prototype.cancel = function() {
 Blockly.Gesture.prototype.handleRightClick = function(e) {
   if (this.targetBlock_) {
     this.bringBlockToFront_();
-    Blockly.hideChaff(this.flyout_);
+    Blockly.hideChaff(!!this.flyout_);
     this.targetBlock_.showContextMenu_(e);
   } else if (this.startBubble_) {
     this.startBubble_.showContextMenu_(e);
diff --git a/core/inject.js b/core/inject.js
index 2019bc1d9..1d9b72f8b 100644
--- a/core/inject.js
+++ b/core/inject.js
@@ -41,10 +41,10 @@ goog.require('Blockly.WorkspaceSvg');
 
 /**
  * Inject a Blockly editor into the specified container element (usually a div).
- * @param {!Element|string} container Containing element, or its ID,
+ * @param {Element|string} container Containing element, or its ID,
  *     or a CSS selector.
  * @param {Object=} opt_options Optional dictionary of options.
- * @return {!Blockly.Workspace} Newly created main workspace.
+ * @return {!Blockly.WorkspaceSvg} Newly created main workspace.
  */
 Blockly.inject = function(container, opt_options) {
   Blockly.checkBlockColourConstants();
@@ -54,7 +54,7 @@ Blockly.inject = function(container, opt_options) {
         document.querySelector(container);
   }
   // Verify that the container is in document.
-  if (!Blockly.utils.dom.containsNode(document, container)) {
+  if (!container || !Blockly.utils.dom.containsNode(document, container)) {
     throw Error('Error: container is not in current document.');
   }
   var options = new Blockly.Options(opt_options || {});
@@ -206,7 +206,7 @@ Blockly.createDom_ = function(container, options) {
  *     for the blocks.
  * @param {!Blockly.WorkspaceDragSurfaceSvg} workspaceDragSurface Drag surface
  *     SVG for the workspace.
- * @return {!Blockly.Workspace} Newly created main workspace.
+ * @return {!Blockly.WorkspaceSvg} Newly created main workspace.
  * @private
  */
 Blockly.createMainWorkspace_ = function(svg, options, blockDragSurface,
@@ -219,7 +219,7 @@ Blockly.createMainWorkspace_ = function(svg, options, blockDragSurface,
 
   if (!options.hasCategories && options.languageTree) {
     // Add flyout as an <svg> that is a sibling of the workspace svg.
-    var flyout = mainWorkspace.addFlyout_('svg');
+    var flyout = mainWorkspace.addFlyout('svg');
     Blockly.utils.dom.insertAfter(flyout, svg);
   }
   if (options.hasTrashcan) {
@@ -385,7 +385,7 @@ Blockly.createMainWorkspace_ = function(svg, options, blockDragSurface,
 
 /**
  * Initialize Blockly with various handlers.
- * @param {!Blockly.Workspace} mainWorkspace Newly created main workspace.
+ * @param {!Blockly.WorkspaceSvg} mainWorkspace Newly created main workspace.
  * @private
  */
 Blockly.init_ = function(mainWorkspace) {
@@ -393,7 +393,8 @@ Blockly.init_ = function(mainWorkspace) {
   var svg = mainWorkspace.getParentSvg();
 
   // Suppress the browser's context menu.
-  Blockly.bindEventWithChecks_(svg.parentNode, 'contextmenu', null,
+  Blockly.bindEventWithChecks_(
+      /** @type {!Element} */ (svg.parentNode), 'contextmenu', null,
       function(e) {
         if (!Blockly.utils.isTargetInput(e)) {
           e.preventDefault();
@@ -411,13 +412,15 @@ Blockly.init_ = function(mainWorkspace) {
   Blockly.inject.bindDocumentEvents_();
 
   if (options.languageTree) {
-    if (mainWorkspace.getToolbox()) {
-      mainWorkspace.getToolbox().init(mainWorkspace);
-    } else if (mainWorkspace.flyout_) {
+    var toolbox = mainWorkspace.getToolbox();
+    var flyout = mainWorkspace.getFlyout(true);
+    if (toolbox) {
+      toolbox.init();
+    } else if (flyout) {
       // Build a fixed flyout with the root blocks.
-      mainWorkspace.flyout_.init(mainWorkspace);
-      mainWorkspace.flyout_.show(options.languageTree.childNodes);
-      mainWorkspace.flyout_.scrollToStart();
+      flyout.init(mainWorkspace);
+      flyout.show(options.languageTree.childNodes);
+      flyout.scrollToStart();
     }
   }
 
@@ -452,6 +455,7 @@ Blockly.init_ = function(mainWorkspace) {
  * Also, 'keydown' has to be on the whole document since the browser doesn't
  * understand a concept of focus on the SVG image.
  * @private
+ * @suppress {deprecated} Suppress deprecated bindEvent_ call.
  */
 Blockly.inject.bindDocumentEvents_ = function() {
   if (!Blockly.documentEventsBound_) {
@@ -463,7 +467,7 @@ Blockly.inject.bindDocumentEvents_ = function() {
         }
       }
     });
-    Blockly.bindEventWithChecks_(document, 'keydown', null, Blockly.onKeyDown_);
+    Blockly.bindEventWithChecks_(document, 'keydown', null, Blockly.onKeyDown);
     // longStop needs to run to stop the context menu from showing up.  It
     // should run regardless of what other touch event handlers have run.
     Blockly.bindEvent_(document, 'touchend', null, Blockly.longStop_);
@@ -473,7 +477,8 @@ Blockly.inject.bindDocumentEvents_ = function() {
       Blockly.bindEventWithChecks_(window, 'orientationchange', document,
           function() {
             // TODO (#397): Fix for multiple Blockly workspaces.
-            Blockly.svgResize(Blockly.getMainWorkspace());
+            Blockly.svgResize(/** @type {!Blockly.WorkspaceSvg} */
+                (Blockly.getMainWorkspace()));
           });
     }
   }
diff --git a/core/mutator.js b/core/mutator.js
index 8b6bbd7d8..af5d9e0b9 100644
--- a/core/mutator.js
+++ b/core/mutator.js
@@ -141,7 +141,7 @@ Blockly.Mutator.prototype.createEditor_ = function() {
   } else {
     var quarkXml = null;
   }
-  var workspaceOptions = {
+  var workspaceOptions = /** @type {!Blockly.Options} */ ({
     // If you want to enable disabling, also remove the
     // event filter from workspaceChanged_ .
     disable: false,
@@ -156,7 +156,7 @@ Blockly.Mutator.prototype.createEditor_ = function() {
     getMetrics: this.getFlyoutMetrics_.bind(this),
     setMetrics: null,
     renderer: this.block_.workspace.options.renderer
-  };
+  });
   this.workspace_ = new Blockly.WorkspaceSvg(workspaceOptions);
   this.workspace_.isMutator = true;
   this.workspace_.addChangeListener(Blockly.Events.disableOrphans);
@@ -165,7 +165,7 @@ Blockly.Mutator.prototype.createEditor_ = function() {
   // a top level svg. Instead of handling scale themselves, mutators
   // inherit scale from the parent workspace.
   // To fix this, scale needs to be applied at a different level in the dom.
-  var flyoutSvg = this.workspace_.addFlyout_('g');
+  var flyoutSvg = this.workspace_.addFlyout('g');
   var background = this.workspace_.createDom('blocklyMutatorBackground');
 
   // Insert the flyout after the <rect> but before the block canvas so that
@@ -215,8 +215,9 @@ Blockly.Mutator.prototype.resizeBubble_ = function() {
     width = workspaceSize.width + workspaceSize.x;
   }
   var height = workspaceSize.height + doubleBorderWidth * 3;
-  if (this.workspace_.flyout_) {
-    var flyoutMetrics = this.workspace_.flyout_.getMetrics_();
+  var flyout = this.workspace_.getFlyout();
+  if (flyout) {
+    var flyoutMetrics = flyout.getMetrics_();
     height = Math.max(height, flyoutMetrics.contentHeight + 20);
   }
   width += doubleBorderWidth * 3;
@@ -260,9 +261,10 @@ Blockly.Mutator.prototype.setVisible = function(visible) {
     // Expose this mutator's block's ID on its top-level SVG group.
     this.bubble_.setSvgId(this.block_.id);
     var tree = this.workspace_.options.languageTree;
+    var flyout = this.workspace_.getFlyout();
     if (tree) {
-      this.workspace_.flyout_.init(this.workspace_);
-      this.workspace_.flyout_.show(tree.childNodes);
+      flyout.init(this.workspace_);
+      flyout.show(tree.childNodes);
     }
 
     this.rootBlock_ = this.block_.decompose(this.workspace_);
@@ -273,9 +275,9 @@ Blockly.Mutator.prototype.setVisible = function(visible) {
     // The root block should not be dragable or deletable.
     this.rootBlock_.setMovable(false);
     this.rootBlock_.setDeletable(false);
-    if (this.workspace_.flyout_) {
-      var margin = this.workspace_.flyout_.CORNER_RADIUS * 2;
-      var x = this.workspace_.getFlyout().getWidth() + margin;
+    if (flyout) {
+      var margin = flyout.CORNER_RADIUS * 2;
+      var x = flyout.getWidth() + margin;
     } else {
       var margin = 16;
       var x = margin;
@@ -427,7 +429,7 @@ Blockly.Mutator.prototype.updateBlockStyle = function() {
       block.setStyle(block.getStyleName());
     }
 
-    var flyoutBlocks = ws.flyout_.workspace_.getAllBlocks(false);
+    var flyoutBlocks = ws.getFlyout().workspace_.getAllBlocks(false);
     for (var i = 0; i < flyoutBlocks.length; i++) {
       var block = flyoutBlocks[i];
       block.setStyle(block.getStyleName());
diff --git a/core/scrollbar.js b/core/scrollbar.js
index 4042635e9..92ae14164 100644
--- a/core/scrollbar.js
+++ b/core/scrollbar.js
@@ -627,9 +627,12 @@ Blockly.Scrollbar.prototype.createDom_ = function(opt_class) {
         'ry': radius
       },
       this.svgGroup_);
-  this.workspace_.getThemeManager().subscribe(this.svgHandle_, 'scrollbar', 'fill');
-  this.workspace_.getThemeManager().subscribe(this.svgHandle_, 'scrollbarOpacity', 'fill-opacity');
-  Blockly.utils.dom.insertAfter(this.outerSvg_, this.workspace_.getParentSvg());
+  this.workspace_.getThemeManager().subscribe(
+      this.svgHandle_, 'scrollbar', 'fill');
+  this.workspace_.getThemeManager().subscribe(
+      this.svgHandle_, 'scrollbarOpacity', 'fill-opacity');
+  Blockly.utils.dom.insertAfter(this.outerSvg_,
+      this.workspace_.getParentSvg());
 };
 
 /**
@@ -711,7 +714,8 @@ Blockly.Scrollbar.prototype.onMouseDownBar_ = function(e) {
     e.stopPropagation();
     return;
   }
-  var mouseXY = Blockly.utils.mouseToSvg(e, this.workspace_.getParentSvg(),
+  var mouseXY = Blockly.utils.mouseToSvg(e,
+      this.workspace_.getParentSvg(),
       this.workspace_.getInverseScreenCTM());
   var mouseLocation = this.horizontal_ ? mouseXY.x : mouseXY.y;
 
diff --git a/core/toolbox.js b/core/toolbox.js
index 046cfb345..448eded68 100644
--- a/core/toolbox.js
+++ b/core/toolbox.js
@@ -110,6 +110,13 @@ Blockly.Toolbox = function(workspace) {
         'blocklyHorizontalTreeRtl' : 'blocklyHorizontalTree');
     this.config_['cssTreeIcon'] = '';
   }
+
+  /**
+   * The toolbox flyout.
+   * @type {Blockly.Flyout}
+   * @private
+   */
+  this.flyout_ = null;
 };
 
 /**
@@ -140,6 +147,8 @@ Blockly.Toolbox.prototype.lastCategory_ = null;
 
 /**
  * Initializes the toolbox.
+ * @throws {Error} If missing a require for both `Blockly.HorizontalFlyout` and
+ *     `Blockly.VerticalFlyout`.
  */
 Blockly.Toolbox.prototype.init = function() {
   var workspace = this.workspace_;
@@ -178,11 +187,6 @@ Blockly.Toolbox.prototype.init = function() {
     toolboxPosition: workspace.options.toolboxPosition,
     renderer: workspace.options.renderer
   };
-  /**
-   * @type {!Blockly.Flyout}
-   * @private
-   */
-  this.flyout_ = null;
   if (workspace.horizontalLayout) {
     if (!Blockly.HorizontalFlyout) {
       throw Error('Missing require for Blockly.HorizontalFlyout');
@@ -194,9 +198,13 @@ Blockly.Toolbox.prototype.init = function() {
     }
     this.flyout_ = new Blockly.VerticalFlyout(workspaceOptions);
   }
+  if (!this.flyout_) {
+    throw Error('One of Blockly.VerticalFlyout or Blockly.Horizontal must be' +
+        'required.');
+  }
+  
   // Insert the flyout after the workspace.
-  Blockly.utils.dom.insertAfter(this.flyout_.createDom('svg'),
-      this.workspace_.getParentSvg());
+  Blockly.utils.dom.insertAfter(this.flyout_.createDom('svg'), svg);
   this.flyout_.init(workspace);
 
   this.config_['cleardotPath'] = workspace.options.pathToMedia + '1x1.gif';
@@ -207,7 +215,7 @@ Blockly.Toolbox.prototype.init = function() {
 
 /**
  * Fill the toolbox with categories and blocks.
- * @param {!Node} languageTree DOM tree of blocks.
+ * @param {Node} languageTree DOM tree of blocks.
  * @package
  */
 Blockly.Toolbox.prototype.renderTree = function(languageTree) {
@@ -225,8 +233,8 @@ Blockly.Toolbox.prototype.renderTree = function(languageTree) {
   if (languageTree) {
     this.tree_.blocks = [];
     this.hasColours_ = false;
-    var openNode =
-      this.syncTrees_(languageTree, this.tree_, this.workspace_.options.pathToMedia);
+    openNode = this.syncTrees_(
+        languageTree, this.tree_, this.workspace_.options.pathToMedia);
 
     if (this.tree_.blocks.length) {
       throw Error('Toolbox cannot have both blocks and categories ' +
@@ -245,7 +253,8 @@ Blockly.Toolbox.prototype.renderTree = function(languageTree) {
   // Trees have an implicit orientation of vertical, so we only need to set this
   // when the toolbox is in horizontal mode.
   if (this.horizontalLayout_) {
-    Blockly.utils.aria.setState(/** @type {!Element} */ (this.tree_.getElement()),
+    Blockly.utils.aria.setState(
+        /** @type {!Element} */ (this.tree_.getElement()),
         Blockly.utils.aria.State.ORIENTATION, 'horizontal');
   }
 };
@@ -353,7 +362,6 @@ Blockly.Toolbox.prototype.dispose = function() {
   this.tree_.dispose();
   this.workspace_.getThemeManager().unsubscribe(this.HtmlDiv);
   Blockly.utils.dom.removeNode(this.HtmlDiv);
-  this.workspace_ = null;
   this.lastCategory_ = null;
 };
 
@@ -373,6 +381,14 @@ Blockly.Toolbox.prototype.getHeight = function() {
   return this.height;
 };
 
+/**
+ * Get the toolbox flyout.
+ * @return {Blockly.Flyout} The toolbox flyout.
+ */
+Blockly.Toolbox.prototype.getFlyout = function() {
+  return this.flyout_;
+};
+
 /**
  * Move the toolbox to the edge.
  */
@@ -382,8 +398,7 @@ Blockly.Toolbox.prototype.position = function() {
     // Not initialized yet.
     return;
   }
-  var svg = this.workspace_.getParentSvg();
-  var svgSize = Blockly.svgSize(svg);
+  var svgSize = Blockly.svgSize(this.workspace_.getParentSvg());
   if (this.horizontalLayout_) {
     treeDiv.style.left = '0';
     treeDiv.style.height = 'auto';
@@ -474,7 +489,8 @@ Blockly.Toolbox.prototype.syncTrees_ = function(treeIn, treeOut, pathToMedia) {
           // Separator between two categories.
           // <sep></sep>
           treeOut.add(new Blockly.Toolbox.TreeSeparator(
-              /** @type {!Blockly.tree.BaseNode.Config} */ (this.treeSeparatorConfig_)));
+              /** @type {!Blockly.tree.BaseNode.Config} */
+              (this.treeSeparatorConfig_)));
           break;
         }
         // Otherwise falls through.
diff --git a/core/trashcan.js b/core/trashcan.js
index a452d2004..fecc23a06 100644
--- a/core/trashcan.js
+++ b/core/trashcan.js
@@ -31,13 +31,13 @@ goog.require('Blockly.Xml');
 
 /**
  * Class for a trash can.
- * @param {!Blockly.Workspace} workspace The workspace to sit in.
+ * @param {!Blockly.WorkspaceSvg} workspace The workspace to sit in.
  * @constructor
  */
 Blockly.Trashcan = function(workspace) {
   /**
    * The workspace the trashcan sits in.
-   * @type {!Blockly.Workspace}
+   * @type {!Blockly.WorkspaceSvg}
    * @private
    */
   this.workspace_ = workspace;
@@ -49,6 +49,12 @@ Blockly.Trashcan = function(workspace) {
    */
   this.contents_ = [];
 
+  /**
+   * The trashcan flyout.
+   * @type {Blockly.Flyout}
+   * @package
+   */
+  this.flyout = null;
 
   if (this.workspace_.options.maxTrashcanContents <= 0) {
     return;
@@ -70,7 +76,7 @@ Blockly.Trashcan = function(workspace) {
     if (!Blockly.HorizontalFlyout) {
       throw Error('Missing require for Blockly.HorizontalFlyout');
     }
-    this.flyout_ = new Blockly.HorizontalFlyout(flyoutWorkspaceOptions);
+    this.flyout = new Blockly.HorizontalFlyout(flyoutWorkspaceOptions);
   } else {
     flyoutWorkspaceOptions.toolboxPosition =
       this.workspace_.toolboxPosition == Blockly.TOOLBOX_AT_RIGHT ?
@@ -78,7 +84,7 @@ Blockly.Trashcan = function(workspace) {
     if (!Blockly.VerticalFlyout) {
       throw Error('Missing require for Blockly.VerticalFlyout');
     }
-    this.flyout_ = new Blockly.VerticalFlyout(flyoutWorkspaceOptions);
+    this.flyout = new Blockly.VerticalFlyout(flyoutWorkspaceOptions);
   }
   this.workspace_.addChangeListener(this.onDelete_.bind(this));
 };
@@ -284,9 +290,9 @@ Blockly.Trashcan.prototype.createDom = function() {
  */
 Blockly.Trashcan.prototype.init = function(verticalSpacing) {
   if (this.workspace_.options.maxTrashcanContents > 0) {
-    Blockly.utils.dom.insertAfter(this.flyout_.createDom('svg'),
+    Blockly.utils.dom.insertAfter(this.flyout.createDom('svg'),
         this.workspace_.getParentSvg());
-    this.flyout_.init(this.workspace_);
+    this.flyout.init(this.workspace_);
   }
 
   this.verticalSpacing_ = this.MARGIN_BOTTOM_ + verticalSpacing;
@@ -426,7 +432,7 @@ Blockly.Trashcan.prototype.click = function() {
   for (var i = 0, text; text = this.contents_[i]; i++) {
     xml[i] = Blockly.Xml.textToDom(text);
   }
-  this.flyout_.show(xml);
+  this.flyout.show(xml);
 };
 
 /**
diff --git a/core/workspace.js b/core/workspace.js
index cefd46038..32cbbdd00 100644
--- a/core/workspace.js
+++ b/core/workspace.js
@@ -848,6 +848,15 @@ Blockly.Workspace.prototype.getVariableMap = function() {
   return this.variableMap_;
 };
 
+/**
+ * Set the map of all variables on the workspace.
+ * @param {Blockly.VariableMap} variableMap The variable map.
+ * @package
+ */
+Blockly.Workspace.prototype.setVariableMap = function(variableMap) {
+  this.variableMap_ = variableMap;
+};
+
 /**
  * Database of all workspaces.
  * @private
diff --git a/core/workspace_drag_surface_svg.js b/core/workspace_drag_surface_svg.js
index 9e33f2ae7..70a5dd360 100644
--- a/core/workspace_drag_surface_svg.js
+++ b/core/workspace_drag_surface_svg.js
@@ -121,7 +121,7 @@ Blockly.WorkspaceDragSurfaceSvg.prototype.translateSurface = function(x, y) {
  * @package
  */
 Blockly.WorkspaceDragSurfaceSvg.prototype.getSurfaceTranslation = function() {
-  return Blockly.utils.getRelativeXY(this.SVG_);
+  return Blockly.utils.getRelativeXY(/** @type {!SVGElement} */ (this.SVG_));
 };
 
 /**
@@ -136,8 +136,8 @@ Blockly.WorkspaceDragSurfaceSvg.prototype.clearAndHide = function(newSurface) {
     throw Error('Couldn\'t clear and hide the drag surface: missing ' +
         'new surface.');
   }
-  var blockCanvas = this.SVG_.childNodes[0];
-  var bubbleCanvas = this.SVG_.childNodes[1];
+  var blockCanvas = /** @type {!Element} */ (this.SVG_.childNodes[0]);
+  var bubbleCanvas = /** @type {!Element} */ (this.SVG_.childNodes[1]);
   if (!blockCanvas || !bubbleCanvas ||
       !Blockly.utils.dom.hasClass(blockCanvas, 'blocklyBlockCanvas') ||
       !Blockly.utils.dom.hasClass(bubbleCanvas, 'blocklyBubbleCanvas')) {
diff --git a/core/workspace_dragger.js b/core/workspace_dragger.js
index 67527322f..01b97955f 100644
--- a/core/workspace_dragger.js
+++ b/core/workspace_dragger.js
@@ -46,7 +46,7 @@ Blockly.WorkspaceDragger = function(workspace) {
    * The scroll position of the workspace at the beginning of the drag.
    * Coordinate system: pixel coordinates.
    * @type {!Blockly.utils.Coordinate}
-   * @private
+   * @protected
    */
   this.startScrollXY_ = new Blockly.utils.Coordinate(
       workspace.scrollX, workspace.scrollY);
diff --git a/core/workspace_svg.js b/core/workspace_svg.js
index dc8c3216f..b16fe82a6 100644
--- a/core/workspace_svg.js
+++ b/core/workspace_svg.js
@@ -136,6 +136,13 @@ Blockly.WorkspaceSvg = function(options,
    * @private
    */
   this.renderer_ = Blockly.blockRendering.init(this.options.renderer || 'geras');
+
+  /**
+   * Cached parent SVG.
+   * @type {SVGElement}
+   * @private
+   */
+  this.cachedParentSvg_ = null;
 };
 Blockly.utils.object.inherits(Blockly.WorkspaceSvg, Blockly.Workspace);
 
@@ -346,7 +353,7 @@ Blockly.WorkspaceSvg.prototype.isDragSurfaceActive_ = false;
 /**
  * The first parent div with 'injectionDiv' in the name, or null if not set.
  * Access this with getInjectionDiv.
- * @type {!Element}
+ * @type {Element}
  * @private
  */
 Blockly.WorkspaceSvg.prototype.injectionDiv_ = null;
@@ -355,7 +362,7 @@ Blockly.WorkspaceSvg.prototype.injectionDiv_ = null;
  * Last known position of the page scroll.
  * This is used to determine whether we have recalculated screen coordinate
  * stuff since the page scrolled.
- * @type {!Blockly.utils.Coordinate}
+ * @type {Blockly.utils.Coordinate}
  * @private
  */
 Blockly.WorkspaceSvg.prototype.lastRecordedPageScroll_ = null;
@@ -381,7 +388,7 @@ Blockly.WorkspaceSvg.prototype.toolboxCategoryCallbacks_ = {};
  * workspace's context menu or edit the workspace-created set of menu options.
  * @param {!Array.<!Object>} options List of menu options to add to.
  */
-Blockly.WorkspaceSvg.prototype.configureContextMenu = null;
+Blockly.WorkspaceSvg.prototype.configureContextMenu;
 
 /**
  * In a flyout, the target workspace where blocks should be placed after a drag.
@@ -545,7 +552,7 @@ Blockly.WorkspaceSvg.prototype.getSvgXY = function(element) {
     }
     x += xy.x * scale;
     y += xy.y * scale;
-    element = element.parentNode;
+    element = /** @type {!Element} */ (element.parentNode);
   } while (element && element != this.getParentSvg());
   return new Blockly.utils.Coordinate(x, y);
 };
@@ -565,6 +572,8 @@ Blockly.WorkspaceSvg.prototype.getOriginOffsetInPixels = function() {
 /**
  * Return the injection div that is a parent of this workspace.
  * Walks the DOM the first time it's called, then returns a cached value.
+ * Note: We assume this is only called after the workspace has been injected
+ * into the DOM.
  * @return {!Element} The first parent div with 'injectionDiv' in the name.
  * @package
  */
@@ -579,10 +588,10 @@ Blockly.WorkspaceSvg.prototype.getInjectionDiv = function() {
         this.injectionDiv_ = element;
         break;
       }
-      element = element.parentNode;
+      element = /** @type {!Element} */ (element.parentNode);
     }
   }
-  return this.injectionDiv_;
+  return /** @type {!Element} */ (this.injectionDiv_);
 };
 
 /**
@@ -790,9 +799,9 @@ Blockly.WorkspaceSvg.prototype.addZoomControls = function() {
  * Add a flyout element in an element with the given tag name.
  * @param {string} tagName What type of tag the flyout belongs in.
  * @return {!Element} The element containing the flyout DOM.
- * @private
+ * @package
  */
-Blockly.WorkspaceSvg.prototype.addFlyout_ = function(tagName) {
+Blockly.WorkspaceSvg.prototype.addFlyout = function(tagName) {
   var workspaceOptions = {
     disabledPatternId: this.options.disabledPatternId,
     parentWorkspace: this,
@@ -825,15 +834,16 @@ Blockly.WorkspaceSvg.prototype.addFlyout_ = function(tagName) {
  * Getter for the flyout associated with this workspace.  This flyout may be
  * owned by either the toolbox or the workspace, depending on toolbox
  * configuration.  It will be null if there is no flyout.
+ * @param {boolean=} opt_own Only return the workspace's own flyout if True.
  * @return {Blockly.Flyout} The flyout on this workspace.
  * @package
  */
-Blockly.WorkspaceSvg.prototype.getFlyout = function() {
-  if (this.flyout_) {
+Blockly.WorkspaceSvg.prototype.getFlyout = function(opt_own) {
+  if (this.flyout_ || opt_own) {
     return this.flyout_;
   }
   if (this.toolbox_) {
-    return this.toolbox_.flyout_;
+    return this.toolbox_.getFlyout();
   }
   return null;
 };
@@ -935,21 +945,22 @@ Blockly.WorkspaceSvg.prototype.getBubbleCanvas = function() {
 
 /**
  * Get the SVG element that contains this workspace.
- * @return {SVGElement} SVG element.
+ * Note: We assume this is only called after the workspace has been injected
+ * into the DOM.
+ * @return {!SVGElement} SVG element.
  */
 Blockly.WorkspaceSvg.prototype.getParentSvg = function() {
-  if (this.cachedParentSvg_) {
-    return this.cachedParentSvg_;
-  }
-  var element = this.svgGroup_;
-  while (element) {
-    if (element.tagName == 'svg') {
-      this.cachedParentSvg_ = element;
-      return element;
+  if (!this.cachedParentSvg_) {
+    var element = this.svgGroup_;
+    while (element) {
+      if (element.tagName == 'svg') {
+        this.cachedParentSvg_ = element;
+        break;
+      }
+      element = /** @type {!SVGElement} */ (element.parentNode);
     }
-    element = /** @type {!SVGElement} */ (element.parentNode);
   }
-  return null;
+  return /** @type {!SVGElement} */ (this.cachedParentSvg_);
 };
 
 /**
@@ -1283,7 +1294,7 @@ Blockly.WorkspaceSvg.prototype.pasteWorkspaceComment_ = function(xmlComment) {
  */
 Blockly.WorkspaceSvg.prototype.refreshToolboxSelection = function() {
   var ws = this.isFlyout ? this.targetWorkspace : this;
-  if (ws && !ws.currentGesture_ && ws.toolbox_ && ws.toolbox_.flyout_) {
+  if (ws && !ws.currentGesture_ && ws.toolbox_ && ws.toolbox_.getFlyout()) {
     ws.toolbox_.refreshSelection();
   }
 };
@@ -1889,9 +1900,9 @@ Blockly.WorkspaceSvg.prototype.zoomToFit = function() {
     // the flyout, and the area we want to fit them includes the portion of
     // the workspace that is behind the flyout.
     if (this.horizontalLayout) {
-      workspaceHeight += this.flyout_.height_;
+      workspaceHeight += this.flyout_.getHeight();
       // Convert from pixels to workspace coordinates.
-      blocksHeight += this.flyout_.height_ / this.scale;
+      blocksHeight += this.flyout_.getHeight() / this.scale;
     } else {
       workspaceWidth += this.flyout_.getWidth();
       // Convert from pixels to workspace coordinates.
@@ -2353,6 +2364,17 @@ Blockly.WorkspaceSvg.setTopLevelWorkspaceMetrics_ = function(xyRatio) {
   this.translate(x, y);
 };
 
+/**
+ * Finds the top-level blocks and returns them.  Blocks are optionally sorted
+ * by position; top to bottom (with slight LTR or RTL bias).
+ * @param {boolean} ordered Sort the list if true.
+ * @return {!Array.<!Blockly.BlockSvg>} The top-level block objects.
+ * @override
+ */
+Blockly.WorkspaceSvg.prototype.getTopBlocks = function(ordered) {
+  return Blockly.WorkspaceSvg.superClass_.getTopBlocks.call(this, ordered);
+};
+
 /**
  * Update whether this workspace has resizes enabled.
  * If enabled, workspace will resize when appropriate.