TypeError: webix.CustomScroll is undefined in Line 4029

Webix JS
1

I have just configured a new website to load Webix 2.2.3 and before any Webix specific code is added to the page, I get the the error:

TypeError: webix.CustomScroll is undefined … Line 4029

This is a Webix.Js obtained via the Skin generator.

Firefox latest on Windows 7. Firebug reports the error.

2

Custom Scroll is available in PRO edition only.
Skin-builder provides files for standard version of Webix.

So while the file from skin-builder works correctly in my tests, it will fail with the above message if you will try to init custom scroll.