Style theming is a Beta feature that allows you to customize the look of your mashups and widgets.
do you know if there is already some documentation on how to apply the styles from a theme to a custom widget? I used to work on custom charts and they use style definitions a lot. I want to make them also available for future releases but I have no clue what changed in the widget extension development regarding styling.
A copy of the JS & CSS code of a BETA widget would already be very helpful to do reverse engineering.
It's best to open a separate thread or even a support ticket for this question (as other users could see easier than a response to the "iot tips" doc). But while I don't have a good answer you, perhaps grabbing one of the new widgets that come out with 8.5 and inspecting them through eclipse would help with understanding the style application?
This is an example of a typical path where the widgets are stored in Tomcat:
C:\Program Files\Apache Software Foundation\Tomcat 8.5\webapps\Thingworx\Common\thingworx\widgets