Creating a document reviewing and instant inline commenting application

We will create a document reviewing and commenting application. The document can be an article submission, a comprehension submitted by a student, a thesis paper submitted by a researcher, or anything else that should be reviewed before acceptance. The reviewer can review and insert predefined comments or his/her own custom comments, instantly. The reviewer selects some text in the document, and clicks on any one button (predefined comments) to highlight. Then, the script will highlight the text and insert the comment text inline along with creating an actual comment. You can see the created comments in the Comment panel (at the top right-hand side). Finally, the reviewer can insert score at the end of the document.

As usual, create the onOpen trigger function in the code file, and it will open the sidebar:

function onOpen() {
  var ui = HtmlService.createHtmlOutputFromFile('Sidebar')
    .setTitle('Review and Comment...