Trying to create new tools

[otaviocsantos]

Hi, I'm trying to implement new tools, however I'm having trouble building the example in http://getcontenttools.com/tutorials/adding-new-tools.

I've place time-tool.coffee in ContentTools-master/src/sandbox

and added it to build: files: in Gruntfile.coffee

as included &--time:before { content: "\e94e"; } in _toolbox.scss

Build succeeds and TimeTool appears in content-tools.js at line 5541: var AttributeUI, ContentTools, CropMarksUI, StyleUI, TimeDialog, TimeTool, exports, _EditorApp,

line 9383: TimeTool = (function(_super) {

But I'm getting the error: content-tools.js:5543 Uncaught TypeError: Cannot read property 'prototype' of undefined on Chrome

and: TypeError: parent is undefined on Firefox

OS is Ubuntu 17.

Any clues or tips on what could have gone wrong?