After digging in deeper and rethink the usage of the dashboard designer, I realized that it is my failure to understand correctly the intent of dashboard designer.
It is a page creation tool. The editor is a container that register a list of HTML components. It will update and keeps track of the positioning and the attribute of the elements. The page view is final output which show the layout of HTML components. Changes made via the designer canvas or the generated code will update the page view.
The editor records the order sequence of HTML components which has dragged and dropped in the canvas. The generated code provide information about the HTML components.
It will be a great helper for designing the page quickly. I think I need to spend more time to get familiar with the rich features offered by the dashboard designer.
Thank you for your attention.