Adding custom class to numerictextbox

[Jeremy]

I seem to be having an issue where the numerictextbox widget does not pull the custom class assigned to the original input field. 

The combobox and other widgets seem to do as expected, and add the original class to span.k-widget, however it doesn't seem to be happening ok span.k-widget.k-numerictextbox

Any ideas? Is this a bug, or is this expected behavior? If it is expected, how does one go about adding a custom class (or id) to span.k-widget.k-numerictextbox?

Thanks in advance for your help.

Here's a js fiddle to show you what's happening: http://jsfiddle.net/MCCPs/4/