Included particulars of a writing that is been edited are by default presented in the form of a textual symbol, where memorability is aided by a preview version that can be shown by hovering the mouse pointer over it. An alternative would be to implement a text editor where everything is always presented as it appears publicly, but embeddable particulars that get loaded from elsewhere often do not load immediately. It would be a bit of a slow down and would meaninglessly direct attention to how something is still taking shape while thoughts should be focused on the ideas related to the writing.

That's why so-called "better placeholders" mode is selectable from the editor's Misc menu. Available in views "text editing" and "writing fine-tuning". Location of any placeholder element can be changed as usual in both editor modes, i.e. first the cursor to some position in a writing (preferably between text paragraphs) and then Ctrl-clicking on some placeholder.

Picture 1. Better placeholders mode.
Picture 2. Normal placeholders mode.
Picture 3. Some final layout for a writing using certain width of a browser.