You already know about WordPress Visual editor and HTML editor, they all works in the back-end. Here we are discussing about new WP Smart Editor that works directly in Post Preview Mode which means you can directly edit, write and customize your post content from its preview page itself using this new post editor.
Installation & Usage: Install and activate Smart Editor plugin. The plugin sets up automatically after activation and starts working. There are no configuration options to set.
Step-1 After activation. You can use Smart Editor by visiting your admin area Dashboard -> Posts -> Add New page (or open any old post for editing.)
Step-2 Give your post a title and put your cursor in post content box and click Smart Editor button (present next to Visual & Text editor buttons).
Step-3 Clicking Smart Editor button opens up the preview page of your blog post and you can Edit, Write & Customize all your post content from there itself using new smart editor buttons bar that shows up on the top of the page, below WP admin bar.
The plugin also adds the smart editor button in admin area Dashboard -> Posts -> All Posts page under each post title next to Edit, Quick Edit, Trash & Preview buttons.