A User of Show
July 12, 2019
For those who are wondering why this add-on is well coded but doesn't work as expected:
The issue with Google Add-ons in general, so including this one, is that it only allows to manipulate text. You can indeed modify the UI but everything that is happening in the editable text canvas (which you call your actual document) is predefined by what Google Docs supports. So, what this add-on does as a work-around is fairly simple:
As it can't show UI elements on top of the document (only in the menu bar) its code analyses the text, searches for page breaks, line breaks etc, and adds 'physical' characters into your text. These page-break-characters are identical to your other regular alphabetic or numeric characters.
As scripts (add-ons) can only run and be executed synchronously they only work once until you run them again. So, it adds the characters, you do a new line break, you have to run the code again to make the new line-break-characters to show up again (be added in the text by the code)
I really hope that Google soon extends the capabilities of Docs so it can actually function-wise compete with MS Word. The UI of Google Apps is much cleaner, it's fast, and integrates well with other Google apps. There are only a bunch of simple features missing that are quite essential for a basic but powerful text editor but this could push users away from it, regardless of how much they would like to use it instead.