The Theme Selector component is used to allow users to choose which Theme should be active.
Add a Theme Selector component to the site
Configure a Query based on the Theme Table, and set the on-click link for a field to point to the Theme Selector component. Ensure the record id of the Theme Table is included in the parameters for the link.
Embed the Query on a Page
The user then visits the Page, and clicks on a link in the query. The site then changes to the chosen theme. The user stays on the same page.