diff --git a/blockly_compressed.js b/blockly_compressed.js
index 377b0ac67..40fc0798f 100644
--- a/blockly_compressed.js
+++ b/blockly_compressed.js
@@ -861,10 +861,12 @@ goog.ui.tree.TreeControl.prototype.createNode=function(a){return new goog.ui.tre
 // Copyright 2013 Google Inc.  Apache License 2.0
 var Blockly={Blocks:{}};
 // Copyright 2012 Google Inc.  Apache License 2.0
-Blockly.Workspace=function(a){this.id=Blockly.genUid();Blockly.Workspace.WorkspaceDB_[this.id]=this;this.options=a||{};this.RTL=!!this.options.RTL;this.horizontalLayout=!!this.options.horizontalLayout;this.toolboxPosition=this.options.toolboxPosition;this.topBlocks_=[];this.listeners_=[];this.undoStack_=[];this.redoStack_=[];this.blockDB_=Object.create(null)};Blockly.Workspace.prototype.rendered=!1;Blockly.Workspace.prototype.MAX_UNDO=1024;
-Blockly.Workspace.prototype.dispose=function(){this.listeners_.length=0;this.clear();delete Blockly.Workspace.WorkspaceDB_[this.id]};Blockly.Workspace.SCAN_ANGLE=3;Blockly.Workspace.prototype.addTopBlock=function(a){this.topBlocks_.push(a)};Blockly.Workspace.prototype.removeTopBlock=function(a){for(var b=!1,c,d=0;c=this.topBlocks_[d];d++)if(c==a){this.topBlocks_.splice(d,1);b=!0;break}if(!b)throw"Block not present in workspace's list of top-most blocks.";};
+Blockly.Workspace=function(a){this.id=Blockly.genUid();Blockly.Workspace.WorkspaceDB_[this.id]=this;this.options=a||{};this.RTL=!!this.options.RTL;this.horizontalLayout=!!this.options.horizontalLayout;this.toolboxPosition=this.options.toolboxPosition;this.topBlocks_=[];this.listeners_=[];this.undoStack_=[];this.redoStack_=[];this.blockDB_=Object.create(null);this.variableList=[]};Blockly.Workspace.prototype.rendered=!1;Blockly.Workspace.prototype.MAX_UNDO=1024;
+Blockly.Workspace.prototype.dispose=function(){this.listeners_.length=0;this.clear();delete Blockly.Workspace.WorkspaceDB_[this.id]};Blockly.Workspace.SCAN_ANGLE=3;Blockly.Workspace.prototype.addTopBlock=function(a){this.topBlocks_.push(a);if(this.isFlyout){a=Blockly.Variables.allVariables(a);for(var b=0;b<a.length;b++)-1==this.variableList.indexOf(a[b])&&this.variableList.push(a[b])}};
+Blockly.Workspace.prototype.removeTopBlock=function(a){for(var b=!1,c,d=0;c=this.topBlocks_[d];d++)if(c==a){this.topBlocks_.splice(d,1);b=!0;break}if(!b)throw"Block not present in workspace's list of top-most blocks.";};
 Blockly.Workspace.prototype.getTopBlocks=function(a){var b=[].concat(this.topBlocks_);if(a&&1<b.length){var c=Math.sin(goog.math.toRadians(Blockly.Workspace.SCAN_ANGLE));this.RTL&&(c*=-1);b.sort(function(a,b){var f=a.getRelativeToSurfaceXY(),g=b.getRelativeToSurfaceXY();return f.y+c*f.x-(g.y+c*g.x)})}return b};Blockly.Workspace.prototype.getAllBlocks=function(){for(var a=this.getTopBlocks(!1),b=0;b<a.length;b++)a.push.apply(a,a[b].getChildren());return a};
-Blockly.Workspace.prototype.clear=function(){var a=Blockly.Events.getGroup();for(a||Blockly.Events.setGroup(!0);this.topBlocks_.length;)this.topBlocks_[0].dispose();a||Blockly.Events.setGroup(!1)};Blockly.Workspace.prototype.getWidth=function(){return 0};Blockly.Workspace.prototype.newBlock=function(a,b){return new Blockly.Block(this,a,b)};Blockly.Workspace.prototype.remainingCapacity=function(){return isNaN(this.options.maxBlocks)?Infinity:this.options.maxBlocks-this.getAllBlocks().length};
+Blockly.Workspace.prototype.clear=function(){var a=Blockly.Events.getGroup();for(a||Blockly.Events.setGroup(!0);this.topBlocks_.length;)this.topBlocks_[0].dispose();a||Blockly.Events.setGroup(!1);this.variableList.length=0};Blockly.Workspace.prototype.updateVariableList=function(){if(!this.isFlyout){this.variableList.length=0;for(var a=Blockly.Variables.allVariables(this),b=0;b<a.length;b++)this.variableList.push(a[b])}};
+Blockly.Workspace.prototype.renameVariable=function(a,b){var c=this.variableList.indexOf(a);-1!=c?this.variableList[c]=b:(this.variableList.push(b),console.log("Tried to rename an non-existent variable."))};Blockly.Workspace.prototype.getWidth=function(){return 0};Blockly.Workspace.prototype.newBlock=function(a,b){return new Blockly.Block(this,a,b)};Blockly.Workspace.prototype.remainingCapacity=function(){return isNaN(this.options.maxBlocks)?Infinity:this.options.maxBlocks-this.getAllBlocks().length};
 Blockly.Workspace.prototype.undo=function(a){var b=a?this.redoStack_:this.undoStack_,c=a?this.undoStack_:this.redoStack_,d=b.pop();if(d){for(var e=[d];b.length&&d.group&&d.group==b[b.length-1].group;)e.push(b.pop());for(b=0;d=e[b];b++)c.push(d);e=Blockly.Events.filter(e,a);Blockly.Events.recordUndo=!1;for(b=0;d=e[b];b++)d.run(a);Blockly.Events.recordUndo=!0}};Blockly.Workspace.prototype.clearUndo=function(){this.undoStack_.length=0;this.redoStack_.length=0;Blockly.Events.clearPendingUndo()};
 Blockly.Workspace.prototype.addChangeListener=function(a){this.listeners_.push(a);return a};Blockly.Workspace.prototype.removeChangeListener=function(a){a=this.listeners_.indexOf(a);-1!=a&&this.listeners_.splice(a,1)};Blockly.Workspace.prototype.fireChangeListener=function(a){a.recordUndo&&(this.undoStack_.push(a),this.redoStack_.length=0,this.undoStack_.length>this.MAX_UNDO&&this.undoStack_.unshift());for(var b=0,c;c=this.listeners_[b];b++)c(a)};
 Blockly.Workspace.prototype.getBlockById=function(a){return this.blockDB_[a]||null};Blockly.Workspace.WorkspaceDB_=Object.create(null);Blockly.Workspace.getById=function(a){return Blockly.Workspace.WorkspaceDB_[a]||null};Blockly.Workspace.prototype.clear=Blockly.Workspace.prototype.clear;Blockly.Workspace.prototype.clearUndo=Blockly.Workspace.prototype.clearUndo;Blockly.Workspace.prototype.addChangeListener=Blockly.Workspace.prototype.addChangeListener;
@@ -997,7 +999,7 @@ Blockly.Xml.cloneShadow_=function(a){for(var b=a=a.cloneNode(!0),c;b;)if(b.first
 Blockly.Xml.domToPrettyText=function(a){a=Blockly.Xml.domToText(a).split("<");for(var b="",c=1;c<a.length;c++){var d=a[c];"/"==d[0]&&(b=b.substring(2));a[c]=b+"<"+d;"/"!=d[0]&&"/>"!=d.slice(-2)&&(b+="  ")}a=a.join("\n");a=a.replace(/(<(\w+)\b[^>]*>[^\n]*)\n *<\/\2>/g,"$1</$2>");return a.replace(/^\n/,"")};
 Blockly.Xml.textToDom=function(a){(a=(new DOMParser).parseFromString(a,"text/xml"))&&a.firstChild&&"xml"==a.firstChild.nodeName.toLowerCase()&&a.firstChild===a.lastChild||goog.asserts.fail("Blockly.Xml.textToDom did not obtain a valid XML tree.");return a.firstChild};
 Blockly.Xml.domToWorkspace=function(a,b){if(a instanceof Blockly.Workspace){var c=a;a=b;b=c;console.warn("Deprecated call to Blockly.Xml.domToWorkspace, swap the arguments.")}var d;b.RTL&&(d=b.getWidth());Blockly.Field.startCache();var c=a.childNodes.length,e=Blockly.Events.getGroup();e||Blockly.Events.setGroup(!0);for(var f=0;f<c;f++){var g=a.childNodes[f],h=g.nodeName.toLowerCase();if("block"==h||"shadow"==h&&!Blockly.Events.recordUndo){var h=Blockly.Xml.domToBlock(g,b),k=parseInt(g.getAttribute("x"),
-10),g=parseInt(g.getAttribute("y"),10);isNaN(k)||isNaN(g)||h.moveBy(b.RTL?d-k:k,g)}else"shadow"==h&&goog.asserts.fail("Shadow block cannot be a top-level block.")}e||Blockly.Events.setGroup(!1);Blockly.Field.stopCache()};
+10),g=parseInt(g.getAttribute("y"),10);isNaN(k)||isNaN(g)||h.moveBy(b.RTL?d-k:k,g)}else"shadow"==h&&goog.asserts.fail("Shadow block cannot be a top-level block.")}e||Blockly.Events.setGroup(!1);Blockly.Field.stopCache();b.updateVariableList()};
 Blockly.Xml.domToBlock=function(a,b){if(a instanceof Blockly.Workspace){var c=a;a=b;b=c;console.warn("Deprecated call to Blockly.Xml.domToBlock, swap the arguments.")}Blockly.Events.disable();var d=Blockly.Xml.domToBlockHeadless_(a,b);if(b.rendered){d.setConnectionsHidden(!0);for(var c=d.getDescendants(),e=c.length-1;0<=e;e--)c[e].initSvg();for(e=c.length-1;0<=e;e--)c[e].render(!1);setTimeout(function(){d.workspace&&d.setConnectionsHidden(!1)},1);d.updateDisabled();Blockly.resizeSvgContents(b)}Blockly.Events.enable();
 Blockly.Events.isEnabled()&&Blockly.Events.fire(new Blockly.Events.Create(d));return d};
 Blockly.Xml.domToBlockHeadless_=function(a,b){var c=null,d=a.getAttribute("type");goog.asserts.assert(d,"Block type unspecified: %s",a.outerHTML);for(var e=a.getAttribute("id"),c=b.newBlock(d,e),f=null,e=0,g;g=a.childNodes[e];e++)if(3!=g.nodeType){for(var h=f=null,k=0,m;m=g.childNodes[k];k++)1==m.nodeType&&("block"==m.nodeName.toLowerCase()?f=m:"shadow"==m.nodeName.toLowerCase()&&(h=m));!f&&h&&(f=h);k=g.getAttribute("name");switch(g.nodeName.toLowerCase()){case "mutation":c.domToMutation&&(c.domToMutation(g),
@@ -1272,13 +1274,13 @@ Blockly.FieldDropdown.prototype.dispose=function(){Blockly.WidgetDiv.hideIfOwner
 Blockly.FieldImage.prototype.init=function(){if(!this.fieldGroup_){this.fieldGroup_=Blockly.createSvgElement("g",{},null);this.visible_||(this.fieldGroup_.style.display="none");this.imageElement_=Blockly.createSvgElement("image",{height:this.height_+"px",width:this.width_+"px"},this.fieldGroup_);this.setValue(this.src_);goog.userAgent.GECKO&&(this.rectElement_=Blockly.createSvgElement("rect",{height:this.height_+"px",width:this.width_+"px","fill-opacity":0},this.fieldGroup_));this.sourceBlock_.getSvgRoot().appendChild(this.fieldGroup_);
 var a=this.rectElement_||this.imageElement_;a.tooltip=this.sourceBlock_;Blockly.Tooltip.bindMouseEvents(a)}};Blockly.FieldImage.prototype.dispose=function(){goog.dom.removeNode(this.fieldGroup_);this.rectElement_=this.imageElement_=this.fieldGroup_=null};Blockly.FieldImage.prototype.setTooltip=function(a){(this.rectElement_||this.imageElement_).tooltip=a};Blockly.FieldImage.prototype.getValue=function(){return this.src_};
 Blockly.FieldImage.prototype.setValue=function(a){null!==a&&(this.src_=a,this.imageElement_&&this.imageElement_.setAttributeNS("http://www.w3.org/1999/xlink","xlink:href",goog.isString(a)?a:""))};Blockly.FieldImage.prototype.setText=function(a){null!==a&&(this.text_=a)};Blockly.FieldImage.prototype.render_=function(){};Blockly.FieldNumber=function(a,b,c,d,e){Blockly.FieldNumber.superClass_.constructor.call(this,a,e);this.setConstraints(b,c,d)};goog.inherits(Blockly.FieldNumber,Blockly.FieldTextInput);Blockly.FieldNumber.prototype.setConstraints=function(a,b,c){c=parseFloat(c);this.precision_=isNaN(c)?0:c;a=parseFloat(a);this.min_=isNaN(a)?-Infinity:a;b=parseFloat(b);this.max_=isNaN(b)?Infinity:b;this.setValue(this.callValidator(this.getValue))};
-Blockly.FieldNumber.classValidator=function(a){if(null===a)return null;a=String(a);a=a.replace(/O/ig,"0");a=a.replace(/,/g,"");a=parseFloat(a||0);if(isNaN(a))return null;this.precision_&&Number.isFinite(a)&&(a=Math.round(a/this.precision_)*this.precision_);a=goog.math.clamp(a,this.min_,this.max_);return String(a)};Blockly.Variables={};Blockly.Variables.NAME_TYPE="VARIABLE";Blockly.Variables.allVariables=function(a){var b;if(a.getDescendants)b=a.getDescendants();else if(a.getAllBlocks)b=a.getAllBlocks();else throw"Not Block or Workspace: "+a;a=Object.create(null);for(var c=0;c<b.length;c++)for(var d=b[c].getVars(),e=0;e<d.length;e++){var f=d[e];f&&(a[f.toLowerCase()]=f)}b=[];for(var g in a)b.push(a[g]);return b};
-Blockly.Variables.renameVariable=function(a,b,c){Blockly.Events.setGroup(!0);c=c.getAllBlocks();for(var d=0;d<c.length;d++)c[d].renameVar(a,b);Blockly.Events.setGroup(!1)};
-Blockly.Variables.flyoutCategory=function(a){a=Blockly.Variables.allVariables(a);a.sort(goog.string.caseInsensitiveCompare);goog.array.remove(a,Blockly.Msg.VARIABLES_DEFAULT_NAME);a.unshift(Blockly.Msg.VARIABLES_DEFAULT_NAME);var b=[],c=goog.dom.createDom("button");c.setAttribute("text","Create variable");b.push(c);for(c=0;c<a.length;c++){if(Blockly.Blocks.variables_set){var d=goog.dom.createDom("block");d.setAttribute("type","variables_set");Blockly.Blocks.variables_get&&d.setAttribute("gap",8);
-var e=goog.dom.createDom("field",null,a[c]);e.setAttribute("name","VAR");d.appendChild(e);b.push(d)}Blockly.Blocks.variables_get&&(d=goog.dom.createDom("block"),d.setAttribute("type","variables_get"),Blockly.Blocks.variables_set&&d.setAttribute("gap",24),e=goog.dom.createDom("field",null,a[c]),e.setAttribute("name","VAR"),d.appendChild(e),b.push(d))}return b};
-Blockly.Variables.generateUniqueName=function(a){a=Blockly.Variables.allVariables(a);var b="";if(a.length)for(var c=1,d=0,e="ijkmnopqrstuvwxyzabcdefgh".charAt(d);!b;){for(var f=!1,g=0;g<a.length;g++)if(a[g].toLowerCase()==e){f=!0;break}f?(d++,25==d&&(d=0,c++),e="ijkmnopqrstuvwxyzabcdefgh".charAt(d),1<c&&(e+=c)):b=e}else b="i";return b};Blockly.FieldVariable=function(a,b){Blockly.FieldVariable.superClass_.constructor.call(this,Blockly.FieldVariable.dropdownCreate,b);this.setValue(a||"")};goog.inherits(Blockly.FieldVariable,Blockly.FieldDropdown);Blockly.FieldVariable.prototype.init=function(){this.fieldGroup_||(Blockly.FieldVariable.superClass_.init.call(this),this.getValue()||this.setValue(Blockly.Variables.generateUniqueName(this.sourceBlock_.isInFlyout?this.sourceBlock_.workspace.targetWorkspace:this.sourceBlock_.workspace)))};
+Blockly.FieldNumber.classValidator=function(a){if(null===a)return null;a=String(a);a=a.replace(/O/ig,"0");a=a.replace(/,/g,"");a=parseFloat(a||0);if(isNaN(a))return null;this.precision_&&Number.isFinite(a)&&(a=Math.round(a/this.precision_)*this.precision_);a=goog.math.clamp(a,this.min_,this.max_);return String(a)};Blockly.Variables={};Blockly.Variables.NAME_TYPE="VARIABLE";Blockly.Variables.allVariables=function(a){var b;if(a.getDescendants)b=a.getDescendants();else if(a.getAllBlocks)b=a.getAllBlocks();else throw"Not Block or Workspace: "+a;a=Object.create(null);for(var c=0;c<b.length;c++){var d=b[c].getVars();if(d)for(var e=0;e<d.length;e++){var f=d[e];f&&(a[f.toLowerCase()]=f)}}b=[];for(var g in a)b.push(a[g]);return b};
+Blockly.Variables.renameVariable=function(a,b,c){Blockly.Events.setGroup(!0);for(var d=c.getAllBlocks(),e=0;e<d.length;e++)d[e].renameVar(a,b);Blockly.Events.setGroup(!1);c.renameVariable(a,b)};
+Blockly.Variables.flyoutCategory=function(a){a=a.variableList;a.sort(goog.string.caseInsensitiveCompare);goog.array.remove(a,Blockly.Msg.VARIABLES_DEFAULT_NAME);a.unshift(Blockly.Msg.VARIABLES_DEFAULT_NAME);var b=[],c=goog.dom.createDom("button");c.setAttribute("text","Create variable");b.push(c);for(c=0;c<a.length;c++){if(Blockly.Blocks.variables_set){var d=goog.dom.createDom("block");d.setAttribute("type","variables_set");Blockly.Blocks.variables_get&&d.setAttribute("gap",8);var e=goog.dom.createDom("field",
+null,a[c]);e.setAttribute("name","VAR");d.appendChild(e);b.push(d)}Blockly.Blocks.variables_get&&(d=goog.dom.createDom("block"),d.setAttribute("type","variables_get"),Blockly.Blocks.variables_set&&d.setAttribute("gap",24),e=goog.dom.createDom("field",null,a[c]),e.setAttribute("name","VAR"),d.appendChild(e),b.push(d))}return b};
+Blockly.Variables.generateUniqueName=function(a){a=a.variableList;var b="";if(a.length)for(var c=1,d=0,e="ijkmnopqrstuvwxyzabcdefgh".charAt(d);!b;){for(var f=!1,g=0;g<a.length;g++)if(a[g].toLowerCase()==e){f=!0;break}f?(d++,25==d&&(d=0,c++),e="ijkmnopqrstuvwxyzabcdefgh".charAt(d),1<c&&(e+=c)):b=e}else b="i";return b};Blockly.FieldVariable=function(a,b){Blockly.FieldVariable.superClass_.constructor.call(this,Blockly.FieldVariable.dropdownCreate,b);this.setValue(a||"")};goog.inherits(Blockly.FieldVariable,Blockly.FieldDropdown);Blockly.FieldVariable.prototype.init=function(){this.fieldGroup_||(Blockly.FieldVariable.superClass_.init.call(this),this.getValue()||this.setValue(Blockly.Variables.generateUniqueName(this.sourceBlock_.isInFlyout?this.sourceBlock_.workspace.targetWorkspace:this.sourceBlock_.workspace)))};
 Blockly.FieldVariable.prototype.getValue=function(){return this.getText()};Blockly.FieldVariable.prototype.setValue=function(a){this.sourceBlock_&&Blockly.Events.isEnabled()&&Blockly.Events.fire(new Blockly.Events.Change(this.sourceBlock_,"field",this.name,this.value_,a));this.value_=a;this.setText(a)};
-Blockly.FieldVariable.dropdownCreate=function(){var a=this.sourceBlock_&&this.sourceBlock_.workspace?Blockly.Variables.allVariables(this.sourceBlock_.workspace):[],b=this.getText();b&&-1==a.indexOf(b)&&a.push(b);a.sort(goog.string.caseInsensitiveCompare);a.push(Blockly.Msg.RENAME_VARIABLE);a.push(Blockly.Msg.NEW_VARIABLE);for(var b=[],c=0;c<a.length;c++)b[c]=[a[c],a[c]];return b};
+Blockly.FieldVariable.dropdownCreate=function(){var a=this.sourceBlock_&&this.sourceBlock_.workspace?this.sourceBlock_.workspace.variableList.slice(0):[],b=this.getText();b&&-1==a.indexOf(b)&&a.push(b);a.sort(goog.string.caseInsensitiveCompare);a.push(Blockly.Msg.RENAME_VARIABLE);a.push(Blockly.Msg.NEW_VARIABLE);for(var b=[],c=0;c<a.length;c++)b[c]=[a[c],a[c]];return b};
 Blockly.FieldVariable.classValidator=function(a){function b(a,b){Blockly.hideChaff();var c=window.prompt(a,b);c&&(c=c.replace(/[\s\xa0]+/g," ").replace(/^ | $/g,""),c==Blockly.Msg.RENAME_VARIABLE||c==Blockly.Msg.NEW_VARIABLE)&&(c=null);return c}var c=this.sourceBlock_.workspace;if(a==Blockly.Msg.RENAME_VARIABLE){var d=this.getText();(a=b(Blockly.Msg.RENAME_VARIABLE_TITLE.replace("%1",d),d))&&Blockly.Variables.renameVariable(d,a,c);return null}if(a==Blockly.Msg.NEW_VARIABLE)return(a=b(Blockly.Msg.NEW_VARIABLE_TITLE,
 ""))?(Blockly.Variables.renameVariable(a,a,c),a):null};Blockly.Generator=function(a){this.name_=a;this.FUNCTION_NAME_PLACEHOLDER_REGEXP_=new RegExp(this.FUNCTION_NAME_PLACEHOLDER_,"g")};Blockly.Generator.NAME_TYPE="generated_function";Blockly.Generator.prototype.INFINITE_LOOP_TRAP=null;Blockly.Generator.prototype.STATEMENT_PREFIX=null;Blockly.Generator.prototype.INDENT="  ";Blockly.Generator.prototype.COMMENT_WRAP=60;Blockly.Generator.prototype.ORDER_OVERRIDES=[];
 Blockly.Generator.prototype.workspaceToCode=function(a){a||(console.warn("No workspace specified in workspaceToCode call.  Guessing."),a=Blockly.getMainWorkspace());var b=[];this.init(a);a=a.getTopBlocks(!0);for(var c=0,d;d=a[c];c++){var e=this.blockToCode(d);goog.isArray(e)&&(e=e[0]);e&&(d.outputConnection&&this.scrubNakedValue&&(e=this.scrubNakedValue(e)),b.push(e))}b=b.join("\n");b=this.finish(b);b=b.replace(/^\s+\n/,"");b=b.replace(/\n\s+$/,"\n");return b=b.replace(/[ \t]+\n/g,"\n")};
@@ -1319,11 +1321,11 @@ Blockly.Flyout.prototype.setBackgroundPathHorizontal_=function(a,b){var c=this.t
 Blockly.Flyout.prototype.wheel_=function(a){var b=this.horizontalLayout_?a.deltaX:a.deltaY;if(b){goog.userAgent.GECKO&&(b*=10);var c=this.getMetrics_(),b=this.horizontalLayout_?c.viewLeft+b:c.viewTop+b,b=Math.min(b,this.horizontalLayout_?c.contentWidth-c.viewWidth:c.contentHeight-c.viewHeight),b=Math.max(b,0);this.scrollbar_.set(b)}a.preventDefault();a.stopPropagation()};Blockly.Flyout.prototype.isVisible=function(){return this.svgGroup_&&"block"==this.svgGroup_.style.display};
 Blockly.Flyout.prototype.hide=function(){if(this.isVisible()){this.svgGroup_.style.display="none";for(var a=0,b;b=this.listeners_[a];a++)Blockly.unbindEvent_(b);this.listeners_.length=0;this.reflowWrapper_&&(this.workspace_.removeChangeListener(this.reflowWrapper_),this.reflowWrapper_=null)}};
 Blockly.Flyout.prototype.show=function(a){this.hide();this.clearOldBlocks_();a==Blockly.Variables.NAME_TYPE?a=Blockly.Variables.flyoutCategory(this.workspace_.targetWorkspace):a==Blockly.Procedures.NAME_TYPE&&(a=Blockly.Procedures.flyoutCategory(this.workspace_.targetWorkspace));this.svgGroup_.style.display="block";for(var b=[],c=[],d=this.permanentlyDisabled_.length=0,e;e=a[d];d++)if(e.tagName){var f=e.tagName.toUpperCase();"BLOCK"==f?(f=Blockly.Xml.domToBlock(e,this.workspace_),f.disabled&&this.permanentlyDisabled_.push(f),
-b.push({type:"block",block:f}),e=parseInt(e.getAttribute("gap"),10),c.push(isNaN(e)?3*this.MARGIN:e)):"BUTTON"==f&&(b.push({type:"button",label:e.getAttribute("text")}),c.push(this.MARGIN))}this.layout_(b,c);this.listeners_.push(Blockly.bindEvent_(this.svgBackground_,"mouseover",this,function(){for(var a=this.workspace_.getTopBlocks(!1),b=0,c;c=a[b];b++)c.removeSelect()}));this.horizontalLayout_?this.height_=0:this.width_=0;this.reflow();this.filterForCapacity_();this.position();this.reflowWrapper_=
-this.reflow.bind(this);this.workspace_.addChangeListener(this.reflowWrapper_)};
+b.push({type:"block",block:f}),e=parseInt(e.getAttribute("gap"),10),c.push(isNaN(e)?3*this.MARGIN:e)):"BUTTON"==f&&(e=e.getAttribute("text"),e=new Blockly.FlyoutButton(this.workspace_,e),b.push({type:"button",button:e}),c.push(this.MARGIN))}this.layout_(b,c);this.listeners_.push(Blockly.bindEvent_(this.svgBackground_,"mouseover",this,function(){for(var a=this.workspace_.getTopBlocks(!1),b=0,c;c=a[b];b++)c.removeSelect()}));this.horizontalLayout_?this.height_=0:this.width_=0;this.reflow();this.filterForCapacity_();
+this.position();this.reflowWrapper_=this.reflow.bind(this);this.workspace_.addChangeListener(this.reflowWrapper_)};
 Blockly.Flyout.prototype.layout_=function(a,b){this.workspace_.scale=this.targetWorkspace_.scale;var c=this.MARGIN,d=this.RTL?c:c+Blockly.BlockSvg.TAB_WIDTH;this.horizontalLayout_&&this.RTL&&(a=a.reverse());for(var e=0,f;f=a[e];e++)if("block"==f.type){f=f.block;for(var g=f.getDescendants(),h=0,k;k=g[h];h++)k.isInFlyout=!0;f.render();g=f.getSvgRoot();h=f.getHeightWidth();k=f.outputConnection?Blockly.BlockSvg.TAB_WIDTH:0;this.horizontalLayout_&&(d+=k);f.moveBy(this.horizontalLayout_&&this.RTL?-d:d,
-c);this.horizontalLayout_?d+=h.width+b[e]-k:c+=h.height+b[e];h=Blockly.createSvgElement("rect",{"fill-opacity":0},null);h.tooltip=f;Blockly.Tooltip.bindMouseEvents(h);this.workspace_.getCanvas().insertBefore(h,f.getSvgRoot());f.flyoutRect_=h;this.backgroundButtons_[e]=h;this.addBlockListeners_(g,f,h)}else"button"==f.type&&(f=new Blockly.FlyoutButton(this.workspace_,f.label),g=f.createDom(),f.moveTo(d,c),f.show(),Blockly.bindEvent_(g,"mouseup",f,f.onMouseUp),this.buttons_.push(f),this.horizontalLayout_?
-d+=f.width+b[e]:c+=f.height+b[e])};Blockly.Flyout.prototype.clearOldBlocks_=function(){for(var a=this.workspace_.getTopBlocks(!1),b=0,c;c=a[b];b++)c.workspace==this.workspace_&&c.dispose(!1,!1);for(b=0;a=this.backgroundButtons_[b];b++)goog.dom.removeNode(a);for(b=this.backgroundButtons_.length=0;a=this.buttons_[b];b++)a.dispose();this.buttons_.length=0};
+c);this.horizontalLayout_?d+=h.width+b[e]-k:c+=h.height+b[e];h=Blockly.createSvgElement("rect",{"fill-opacity":0},null);h.tooltip=f;Blockly.Tooltip.bindMouseEvents(h);this.workspace_.getCanvas().insertBefore(h,f.getSvgRoot());f.flyoutRect_=h;this.backgroundButtons_[e]=h;this.addBlockListeners_(g,f,h)}else"button"==f.type&&(f=f.button,g=f.createDom(),f.moveTo(d,c),f.show(),Blockly.bindEvent_(g,"mouseup",f,f.onMouseUp),this.buttons_.push(f),this.horizontalLayout_?d+=f.width+b[e]:c+=f.height+b[e])};
+Blockly.Flyout.prototype.clearOldBlocks_=function(){for(var a=this.workspace_.getTopBlocks(!1),b=0,c;c=a[b];b++)c.workspace==this.workspace_&&c.dispose(!1,!1);for(b=0;a=this.backgroundButtons_[b];b++)goog.dom.removeNode(a);for(b=this.backgroundButtons_.length=0;a=this.buttons_[b];b++)a.dispose();this.buttons_.length=0};
 Blockly.Flyout.prototype.addBlockListeners_=function(a,b,c){this.listeners_.push(Blockly.bindEvent_(a,"mousedown",null,this.blockMouseDown_(b)));this.listeners_.push(Blockly.bindEvent_(c,"mousedown",null,this.blockMouseDown_(b)));this.listeners_.push(Blockly.bindEvent_(a,"mouseover",b,b.addSelect));this.listeners_.push(Blockly.bindEvent_(a,"mouseout",b,b.removeSelect));this.listeners_.push(Blockly.bindEvent_(c,"mouseover",b,b.addSelect));this.listeners_.push(Blockly.bindEvent_(c,"mouseout",b,b.removeSelect))};
 Blockly.Flyout.prototype.blockMouseDown_=function(a){var b=this;return function(c){Blockly.terminateDrag_();Blockly.hideChaff(!0);Blockly.isRightButton(c)?a.showContextMenu_(c):(Blockly.Css.setCursor(Blockly.Css.Cursor.CLOSED),b.startDragMouseY_=c.clientY,b.startDragMouseX_=c.clientX,Blockly.Flyout.startDownEvent_=c,Blockly.Flyout.startBlock_=a,Blockly.Flyout.startFlyout_=b,Blockly.Flyout.onMouseUpWrapper_=Blockly.bindEvent_(document,"mouseup",b,b.onMouseUp_),Blockly.Flyout.onMouseMoveBlockWrapper_=
 Blockly.bindEvent_(document,"mousemove",b,b.onMouseMoveBlock_));c.stopPropagation();c.preventDefault()}};
diff --git a/core/field_variable.js b/core/field_variable.js
index cf903c04c..f0d950ba0 100644
--- a/core/field_variable.js
+++ b/core/field_variable.js
@@ -97,8 +97,9 @@ Blockly.FieldVariable.prototype.setValue = function(newValue) {
  */
 Blockly.FieldVariable.dropdownCreate = function() {
   if (this.sourceBlock_ && this.sourceBlock_.workspace) {
-    var variableList =
-        Blockly.Variables.allVariables(this.sourceBlock_.workspace);
+    // Get a copy of the list, so that adding rename and new variable options
+    // doesn't modify the workspace's list.
+    var variableList = this.sourceBlock_.workspace.variableList.slice(0);
   } else {
     var variableList = [];
   }
diff --git a/core/variables.js b/core/variables.js
index e797b7279..8a6fafa7a 100644
--- a/core/variables.js
+++ b/core/variables.js
@@ -56,11 +56,13 @@ Blockly.Variables.allVariables = function(root) {
   // Iterate through every block and add each variable to the hash.
   for (var x = 0; x < blocks.length; x++) {
     var blockVariables = blocks[x].getVars();
-    for (var y = 0; y < blockVariables.length; y++) {
-      var varName = blockVariables[y];
-      // Variable name may be null if the block is only half-built.
-      if (varName) {
-        variableHash[varName.toLowerCase()] = varName;
+    if (blockVariables) {
+      for (var y = 0; y < blockVariables.length; y++) {
+        var varName = blockVariables[y];
+        // Variable name may be null if the block is only half-built.
+        if (varName) {
+          variableHash[varName.toLowerCase()] = varName;
+        }
       }
     }
   }
@@ -86,6 +88,8 @@ Blockly.Variables.renameVariable = function(oldName, newName, workspace) {
     blocks[i].renameVar(oldName, newName);
   }
   Blockly.Events.setGroup(false);
+
+  workspace.renameVariable(oldName, newName);
 };
 
 /**
@@ -94,7 +98,7 @@ Blockly.Variables.renameVariable = function(oldName, newName, workspace) {
  * @return {!Array.<!Element>} Array of XML block elements.
  */
 Blockly.Variables.flyoutCategory = function(workspace) {
-  var variableList = Blockly.Variables.allVariables(workspace);
+  var variableList = workspace.variableList;
   variableList.sort(goog.string.caseInsensitiveCompare);
   // In addition to the user's variables, we also want to display the default
   // variable name at the top.  We also don't want this duplicated if the
@@ -148,7 +152,7 @@ Blockly.Variables.flyoutCategory = function(workspace) {
 * @return {string} New variable name.
 */
 Blockly.Variables.generateUniqueName = function(workspace) {
-  var variableList = Blockly.Variables.allVariables(workspace);
+  var variableList = workspace.variableList;
   var newName = '';
   if (variableList.length) {
     var nameSuffix = 1;
diff --git a/core/workspace.js b/core/workspace.js
index 200196b70..4d4d635d2 100644
--- a/core/workspace.js
+++ b/core/workspace.js
@@ -73,6 +73,12 @@ Blockly.Workspace = function(opt_options) {
    * @private
    */
   this.blockDB_ = Object.create(null);
+  /*
+   * @type {!Array.<!string>}
+   * A list of all of the named variables in the workspace, including variables
+   * that are not currently in use.
+   */
+  this.variableList = [];
 };
 
 /**
@@ -112,6 +118,14 @@ Blockly.Workspace.SCAN_ANGLE = 3;
  */
 Blockly.Workspace.prototype.addTopBlock = function(block) {
   this.topBlocks_.push(block);
+  if (this.isFlyout) {
+    var variables = Blockly.Variables.allVariables(block);
+    for (var i = 0; i < variables.length; i++) {
+      if (this.variableList.indexOf(variables[i]) == -1) {
+        this.variableList.push(variables[i]);
+      }
+    }
+  }
 };
 
 /**
@@ -181,6 +195,40 @@ Blockly.Workspace.prototype.clear = function() {
   if (!existingGroup) {
     Blockly.Events.setGroup(false);
   }
+
+  this.variableList.length = 0;
+};
+
+/**
+ * Walk the workspace and update the list of variables to only contain ones in
+ * use on the workspace.  Use when loading new workspaces from disk.
+ */
+Blockly.Workspace.prototype.updateVariableList = function() {
+  // TODO: Sort
+  if (!this.isFlyout) {
+    // Update the list in place so that the flyout's references stay correct.
+    this.variableList.length = 0;
+    var allVariables = Blockly.Variables.allVariables(this);
+    for (var i = 0; i < allVariables.length; i++) {
+      this.variableList.push(allVariables[i]);
+    }
+  }
+};
+
+/**
+ * Rename a variable by updating its name in the variable list.
+ * @param {string} oldName Variable to rename.
+ * @param {string} newName New variable name.
+ */
+Blockly.Workspace.prototype.renameVariable = function(oldName, newName) {
+  // Find the old name in the list and replace it.
+  var variableIndex = this.variableList.indexOf(oldName);
+  if (variableIndex != -1) {
+    this.variableList[variableIndex] = newName;
+  } else {
+    this.variableList.push(newName);
+    console.log('Tried to rename an non-existent variable.');
+  }
 };
 
 /**
diff --git a/core/xml.js b/core/xml.js
index 70fd915a5..cd21298f8 100644
--- a/core/xml.js
+++ b/core/xml.js
@@ -313,6 +313,8 @@ Blockly.Xml.domToWorkspace = function(xml, workspace) {
     Blockly.Events.setGroup(false);
   }
   Blockly.Field.stopCache();
+
+  workspace.updateVariableList();
 };
 
 /**
diff --git a/generators/dart.js b/generators/dart.js
index f0d7715ea..cb91dbfd9 100644
--- a/generators/dart.js
+++ b/generators/dart.js
@@ -90,7 +90,7 @@ Blockly.Dart.init = function(workspace) {
   }
 
   var defvars = [];
-  var variables = Blockly.Variables.allVariables(workspace);
+  var variables = workspace.variableList;
   if (variables.length) {
     for (var i = 0; i < variables.length; i++) {
       defvars[i] = Blockly.Dart.variableDB_.getName(variables[i],
diff --git a/generators/javascript.js b/generators/javascript.js
index dcd1f146d..ff50db982 100644
--- a/generators/javascript.js
+++ b/generators/javascript.js
@@ -159,7 +159,7 @@ Blockly.JavaScript.init = function(workspace) {
   }
 
   var defvars = [];
-  var variables = Blockly.Variables.allVariables(workspace);
+  var variables = workspace.variableList;
   if (variables.length) {
     for (var i = 0; i < variables.length; i++) {
       defvars[i] = Blockly.JavaScript.variableDB_.getName(variables[i],
diff --git a/generators/php/procedures.js b/generators/php/procedures.js
index 1fd4cc872..c5ef5ea6d 100644
--- a/generators/php/procedures.js
+++ b/generators/php/procedures.js
@@ -31,7 +31,7 @@ goog.require('Blockly.PHP');
 Blockly.PHP['procedures_defreturn'] = function(block) {
   // Define a procedure with a return value.
   // First, add a 'global' statement for every variable that is assigned.
-  var globals = Blockly.Variables.allVariables(block);
+  var globals = block.workspace.variableList;
   for (var i = globals.length - 1; i >= 0; i--) {
       var varName = globals[i];
       if (block.arguments_.indexOf(varName) == -1) {
diff --git a/generators/python.js b/generators/python.js
index 2e77c0753..60a654f28 100644
--- a/generators/python.js
+++ b/generators/python.js
@@ -129,7 +129,7 @@ Blockly.Python.init = function(workspace) {
   }
 
   var defvars = [];
-  var variables = Blockly.Variables.allVariables(workspace);
+  var variables = workspace.variableList;
   for (var i = 0; i < variables.length; i++) {
     defvars[i] = Blockly.Python.variableDB_.getName(variables[i],
         Blockly.Variables.NAME_TYPE) + ' = None';
diff --git a/generators/python/procedures.js b/generators/python/procedures.js
index daa7386aa..0d000d050 100644
--- a/generators/python/procedures.js
+++ b/generators/python/procedures.js
@@ -32,7 +32,7 @@ goog.require('Blockly.Python');
 Blockly.Python['procedures_defreturn'] = function(block) {
   // Define a procedure with a return value.
   // First, add a 'global' statement for every variable that is assigned.
-  var globals = Blockly.Variables.allVariables(block);
+  var globals = block.workspace.variableList;
   for (var i = globals.length - 1; i >= 0; i--) {
     var varName = globals[i];
     if (block.arguments_.indexOf(varName) == -1) {