Thank you for your feedback.
We do not provide detailed documentation about the elements, attributes and states of a control as actually Visual Style Builder is the tool that has to save your efforts to try to tweak these settings manually in xml. When exposing an element or a state in Visual Style Builder we are trying to put a name as descriptive as possible in order to allow you to easily understand which element is expected to affect what in the big picture. Generally speaking, we have tried to create repository items that explain themselves as well, but it seems that we have some gaps in this direction which we will be amending in future.
I would recommend taking look at our Primitives documentation as these primitives build up the look of RadControls (hence you can encounter them in VSB) and the articles will give you a notion of what these primitives expose as an API. Another element (and its derivatives) used widely in some controls (RadGridView, RadPageView) is LightVisualElement. This element combines the features of several primitives - it can display border, fill, text and image at once.
I want to encourage you to ask us any questions that you may have while working with Visual Style Builder. This will allow us to think of some improvements if such can be implemented. I suppose that you have already got acquainted with our Visual Style Builder documentation. In addition to it, you can take a look at our Visual Style Builder video series that demonstrates styling various RadControls.
Let us know if you have additional questions.
the Telerik team