Ask the user if they are sure they want to load new blocks (replace workspace).

ardublockly/ardublockly.js

@@ -293,12 +293,13 @@ Ardublockly.changeIdeButtons = function(value) {
 };
 
 /**
- * Loads an XML file from the server and adds the blocks into the Blockly
- * workspace.
+ * Loads an XML file from the server and replaces the current blocks into the
+ * Blockly workspace.
  * @param {!string} xmlFile Server location of the XML file to load.
  */
 Ardublockly.loadServerXmlFile = function(xmlFile) {
-  // The loadXmlBlockFile loads the file asynchronously and needs a callback
+  var loadXmlfileAccepted = function() {
+    // loadXmlBlockFile loads the file asynchronously and needs a callback
     var loadXmlCallback = function(sucess) {
       if (sucess) {
         Ardublockly.renderContent();
@@ -315,6 +316,13 @@ Ardublockly.loadServerXmlFile = function(xmlFile) {
     };
     Ardublockly.loadXmlBlockFile(
         xmlFile, loadXmlCallback, callbackConnectionError);
+  };
+
+  Ardublockly.alertMessage(
+      'Load new blocks?',
+      'Loading a new XML file will replace the current blocks from the ' +
+      'workspace.\nAre you sure you want to proceed?',
+      true, loadXmlfileAccepted);
 };
 
 /**

ardublockly/ardublockly_blockly.js

@@ -61,8 +61,8 @@ Ardublockly.bindBlocklyEventListeners = function() {
 };
 
 /**
- * Loads an XML file from the server and adds the blocks into the Blockly
- * workspace.
+ * Loads an XML file from the server and replaces the current blocks into the
+ * Blockly workspace.
  * @param {!string} xmlFile XML file path in a reachable server (no local path).
  * @param {!function} callbackFileLoaded Function to be called once the file is
  *     loaded.