ask anonymous, first-time users to set their name when they first join a pad

www/code/main.js

@@ -198,6 +198,7 @@ define([
                         console.error(err);
                         return;
                     }
+                    module.userName.lastName = myUserName;
                     onLocal();
                 });
             };
@@ -321,12 +322,12 @@ define([
                     editHash = Cryptpad.getEditHashFromKeys(info.channel, secret.keys);
                 }
 
+                // Store the object sent for the "change username" button so that we can update the field value correctly
+                var userNameButtonObject = module.userName = {};
                 /* add a "change username" button */
                 getLastName(function (err, lastName) {
-                    var usernameCb = function (newName) {
-                        setName (newName);
-                    };
-                    var $username = Cryptpad.createButton('username', false, {lastName: lastName}, usernameCb);
+                    userNameButtonObject.lastName = lastName;
+                    var $username = module.$userNameButton = Cryptpad.createButton('username', false, userNameButtonObject, setName);
                     $userBlock.append($username).hide();
                 });
 
@@ -555,6 +556,8 @@ define([
                     addToUserList(myData);
                     if (typeof(lastName) === 'string' && lastName.length) {
                         setName(lastName);
+                    } else {
+                        module.$userNameButton.click();
                     }
                     onLocal();
                 });