Couldn't add child view to box when rendering widgets

[aggFTW]

Hi,

I recently created a kernel that inherits directly from IPythonKernel: class MyKernel(IPythonKernel)
The reason I inherit directly from IPythonKernel and not KernelBase is that I was having trouble getting magics support from KernelBase out of the box.

Anyways, when I try to display a Widget in MyKernel, I get a Javascript error that I am having a very hard time debugging. Message from browser console below. Notice that the widget tabs omit the content of the widget children:

When i run the same piece of code that renders the same widget on the real IPythonKernel, it looks like this, with children displaying correctly:

Any help would be appreciated!

Thanks!

Javascript error message:

Uncaught (in promise) WrappedError {stack: "Error: Couldn't add child view to box↵    at new E…in.js?v=40e10638fcf65fc1c057bff31d165e9d:12785:33", message: "Couldn't add child view to box", error_stack: Array[4]}error_stack: Array[4]0: TypeError: require is not a function
    at http://localhost:8888/static/notebook/js/main.min.js?v=40e10638fcf65fc1c057bff31d165e9d:12740:17
    at Object.load_class (http://localhost:8888/static/notebook/js/main.min.js?v=40e10638fcf65fc1c057bff31d165e9d:12736:16)
    at http://localhost:8888/nbextensions/widgets/widgets/js/manager.js?v=20151103005149:74:261: Error: Couldn't create a view for model id '5ce5e524d89f44fd84f229604853b122'
    at new Error (native)
    at Error.WrappedError (http://localhost:8888/static/notebook/js/main.min.js?v=40e10638fcf65fc1c057bff31d165e9d:12706:25)
    at http://localhost:8888/static/notebook/js/main.min.js?v=40e10638fcf65fc1c057bff31d165e9d:12785:33message: "Couldn't create a view for model id '5ce5e524d89f44fd84f229604853b122'"stack: (...)get stack: ()set stack: ()__proto__: DefineError.bh2: Error: Couldn't create child view
    at new Error (native)
    at Error.WrappedError (http://localhost:8888/static/notebook/js/main.min.js?v=40e10638fcf65fc1c057bff31d165e9d:12706:25)
    at http://localhost:8888/static/notebook/js/main.min.js?v=40e10638fcf65fc1c057bff31d165e9d:12785:33message: "Couldn't create child view"stack: (...)get stack: ()set stack: ()__proto__: DefineError.bh3: Error: Couldn't add child view to box
    at new Error (native)
    at Error.WrappedError (http://localhost:8888/static/notebook/js/main.min.js?v=40e10638fcf65fc1c057bff31d165e9d:12706:25)
    at http://localhost:8888/static/notebook/js/main.min.js?v=40e10638fcf65fc1c057bff31d165e9d:12785:33length: 4__proto__: Array[0]message: "Couldn't add child view to box"stack: "Error: Couldn't add child view to box↵    at new Error (native)↵    at Error.WrappedError (http://localhost:8888/static/notebook/js/main.min.js?v=40e10638fcf65fc1c057bff31d165e9d:12706:25)↵    at http://localhost:8888/static/notebook/js/main.min.js?v=40e10638fcf65fc1c057bff31d165e9d:12785:33"__proto__: Object

[aggFTW]

Hi, friendly ping :)
I don't know if there is an opportunity to refactor the kernel here so that magics work on kernels or if it's just a bug in ipywidgets. I'd appreciate your comments.

Thanks!

[minrk]

This is probably a question for ipywidgets. @jdfreder?

[jdfreder]

Actually I've already been helping @aggFTW in jupyter-widgets/ipywidgets#233 , which is the same issue, in the right repo. We can close this.