An instance of the user-interface environment for a Google App that allows the script to add features like menus, dialogs, and sidebars. A script can only interact with the UI for the current instance of an open editor, and only if the script is container-bound to the editor. Google has made some recent changes to the header feature in Docs. If you just want a header on the first page of your document, remove all headers to get started. Now put your cursor in the header on the first page and check the box for 'different first page.' Google Docs, Sheets, & Slides. On your computer, open a document, spreadsheet, or presentation. Romantic streets. Click Add-ons Manage add-ons. Next to the add-on, click Options Use in this document to turn the add-on on or off. In the top right, click More. In the top right, click Settings Manage Apps. Many of the features that make Google Docs so successful are available through the API. This API lets you read and write documents programmatically so that you can integrate data from various sources leveraging the power of Google Docs.