I have the impression that site builders/admins use a different theme for the admin backend. How cool would it be to be able to preview the changes made to the layout/blocks of the frontend theme as they make changes in the UI?
Here's how Craft CMS does it with their WYSIWYG editor:

We already have a live preview in place for views and another for the color-picker, so perhaps we can abstract and reuse that.
GitHub Issue #:
986
Recent comments
Hi! The description is still very vague and lacks step-by-step instructions on how to reproduce. It doesn't include the version of Backdrop either, nor a list of contrib modules you are using...
Problems with HTML content and text formats
Sorry, it did seem confusing when I read it back... So if I add some html to a text field, for example in a page or a block, whatever the text format of the field may be (raw html or basic...
Problems with HTML content and text formats
Could you please post clear, step by step instructions to reproduce the problem? Your first message refers to HTML content, and your second to text formats. Please add details to reproduce each...
Problems with HTML content and text formats