diff --git a/accessible/toolbox-modal.service.js b/accessible/toolbox-modal.service.js
index a135840eb..63d483d8c 100644
--- a/accessible/toolbox-modal.service.js
+++ b/accessible/toolbox-modal.service.js
@@ -61,44 +61,57 @@ blocklyApp.ToolboxModalService = ng.core.Class({
             'can be shown.');
       };
 
-      // Populate the toolbox categories.
-      this.allToolboxCategories = [];
-      var toolboxXmlElt = document.getElementById('blockly-toolbox-xml');
-      var toolboxCategoryElts = toolboxXmlElt.getElementsByTagName('category');
-      if (toolboxCategoryElts.length) {
-        this.allToolboxCategories = Array.from(toolboxCategoryElts).map(
-          function(categoryElt) {
-            var tmpWorkspace = new Blockly.Workspace();
-            Blockly.Xml.domToWorkspace(categoryElt, tmpWorkspace);
-            return {
-              categoryName: categoryElt.attributes.name.value,
-              blocks: tmpWorkspace.topBlocks_
-            };
-          }
-        );
-        this.computeCategoriesForCreateNewGroupModal_();
-      } else {
-        // A timeout seems to be needed in order for the .children accessor to
-        // work correctly.
-        var that = this;
-        setTimeout(function() {
-          // If there are no top-level categories, we create a single category
-          // containing all the top-level blocks.
-          var tmpWorkspace = new Blockly.Workspace();
-          Array.from(toolboxXmlElt.children).forEach(function(topLevelNode) {
-            Blockly.Xml.domToBlock(tmpWorkspace, topLevelNode);
-          });
-
-          that.allToolboxCategories = [{
-            categoryName: '',
-            blocks: tmpWorkspace.topBlocks_
-          }];
-
-          that.computeCategoriesForCreateNewGroupModal_();
-        });
-      }
+      this.populateToolbox_();
     }
   ],
+  populateToolbox_: function() {
+    // Populate the toolbox categories.
+    this.allToolboxCategories = [];
+    var toolboxXmlElt = document.getElementById('blockly-toolbox-xml');
+    var toolboxCategoryElts = toolboxXmlElt.getElementsByTagName('category');
+    if (toolboxCategoryElts.length) {
+      this.allToolboxCategories = Array.from(toolboxCategoryElts).map(
+        function(categoryElt) {
+          var tmpWorkspace = new Blockly.Workspace();
+          var custom = categoryElt.attributes.custom
+          // TODO (corydiers): Implement custom flyouts once #1153 is solved.
+          if (custom && custom.value == Blockly.VARIABLE_CATEGORY_NAME) {
+            var varBlocks =
+              Blockly.Variables.flyoutCategoryBlocks(blocklyApp.workspace);
+            varBlocks.forEach(function(block) {
+              Blockly.Xml.domToBlock(block, tmpWorkspace);
+            });
+          } else {
+            Blockly.Xml.domToWorkspace(categoryElt, tmpWorkspace);
+          }
+          return {
+            categoryName: categoryElt.attributes.name.value,
+            blocks: tmpWorkspace.topBlocks_
+          };
+        }
+      );
+      this.computeCategoriesForCreateNewGroupModal_();
+    } else {
+      // A timeout seems to be needed in order for the .children accessor to
+      // work correctly.
+      var that = this;
+      setTimeout(function() {
+        // If there are no top-level categories, we create a single category
+        // containing all the top-level blocks.
+        var tmpWorkspace = new Blockly.Workspace();
+        Array.from(toolboxXmlElt.children).forEach(function(topLevelNode) {
+          Blockly.Xml.domToBlock(tmpWorkspace, topLevelNode);
+        });
+
+        that.allToolboxCategories = [{
+          categoryName: '',
+          blocks: tmpWorkspace.topBlocks_
+        }];
+
+        that.computeCategoriesForCreateNewGroupModal_();
+      });
+    }
+  },
   computeCategoriesForCreateNewGroupModal_: function() {
     // Precompute toolbox categories for blocks that have no output
     // connection (and that can therefore be used as the base block of a
@@ -165,6 +178,7 @@ blocklyApp.ToolboxModalService = ng.core.Class({
     var that = this;
 
     var selectedToolboxCategories = [];
+    this.populateToolbox_();
     this.allToolboxCategories.forEach(function(toolboxCategory) {
       var selectedBlocks = toolboxCategory.blocks.filter(function(block) {
         return that.blockConnectionService.canBeAttachedToMarkedConnection(
@@ -202,6 +216,7 @@ blocklyApp.ToolboxModalService = ng.core.Class({
   },
   showToolboxModalForCreateNewGroup: function(sourceButtonId) {
     var that = this;
+    this.populateToolbox_();
     this.showModal_(this.toolboxCategoriesForNewGroup, function(block) {
       var blockDescription = that.utilsService.getBlockDescription(block);
       var xml = Blockly.Xml.blockToDom(block);
diff --git a/build.py b/build.py
index c32e9405b..8abb22c00 100755
--- a/build.py
+++ b/build.py
@@ -115,7 +115,7 @@ window.BLOCKLY_DIR = (function() {
   if (!isNodeJS) {
     // Find name of current directory.
     var scripts = document.getElementsByTagName('script');
-    var re = new RegExp('(.+)[\/]blockly_(.+)uncompressed\.js$');
+    var re = new RegExp('(.+)[\/]blockly_(.*)uncompressed\.js$');
     for (var i = 0, script; script = scripts[i]; i++) {
       var match = re.exec(script.src);
       if (match) {
diff --git a/core/variables.js b/core/variables.js
index 5b3ced3bf..74d3b8e74 100644
--- a/core/variables.js
+++ b/core/variables.js
@@ -101,14 +101,12 @@ Blockly.Variables.allVariables = function(root) {
 };
 
 /**
- * Construct the blocks required by the flyout for the variable category.
+ * Construct the elements (blocks and button) required by the flyout for the
+ * variable category.
  * @param {!Blockly.Workspace} workspace The workspace contianing variables.
- * @return {!Array.<!Element>} Array of XML block elements.
+ * @return {!Array.<!Element>} Array of XML elements.
  */
 Blockly.Variables.flyoutCategory = function(workspace) {
-  var variableModelList = workspace.getVariablesOfType('');
-  variableModelList.sort(Blockly.VariableModel.compareByName);
-
   var xmlList = [];
   var button = goog.dom.createDom('button');
   button.setAttribute('text', Blockly.Msg.NEW_VARIABLE);
@@ -120,6 +118,21 @@ Blockly.Variables.flyoutCategory = function(workspace) {
 
   xmlList.push(button);
 
+  var blockList = Blockly.Variables.flyoutCategoryBlocks(workspace);
+  xmlList = xmlList.concat(blockList);
+  return xmlList;
+};
+
+/**
+ * Construct the blocks required by the flyout for the variable category.
+ * @param {!Blockly.Workspace} workspace The workspace contianing variables.
+ * @return {!Array.<!Element>} Array of XML block elements.
+ */
+Blockly.Variables.flyoutCategoryBlocks = function(workspace) {
+  var variableModelList = workspace.getVariablesOfType('');
+  variableModelList.sort(Blockly.VariableModel.compareByName);
+
+  var xmlList = [];
   if (variableModelList.length > 0) {
     var firstVariable = variableModelList[0];
     if (Blockly.Blocks['variables_set']) {