As you may know, GhostWriter is a free and open-source, distraction-free, markdown editor for Ubuntu.

The latest version available is GhostWriter 1.3.2, which comes with changes.
Main features:
- syntax highlighting of Markdown
- navigation of document headings
- full-screen mode
- focus mode that highlights the current sentence, line, three lines, or paragraph
- two built-in themes, one light and one dark
- theme creator for custom colors and background images
- custom fonts
- spell checking with Hunspell
- live word count
- A live HTML preview as you type
- direct-copy as HTML (useful for blogs, web articles)
- supports custom CSS style sheets for HTML preview
- image URL insertion via dragging and dropping an image file into the editor
- Sundown processor built in for preview and export to HTML
- integrates other Markdown processors (if installed) for preview and export to popular document formats, such as PDF, ODT, and RTF: Pandoc, MultiMarkdown, Discount, cmark
Installation instructions:
In order to successfully install GhostWriter on Ubuntu, you have to add the PPA to your system, update the local repository index and install the ghostwriter package:
$ sudo add-apt-repository ppa:wereturtle/ppa
$ sudo apt-get update
$ sudo apt-get install ghostwriter
Optional, to remove ghostwriter, do:
$ sudo apt-get remove ghostwriter
The installation instructions should work on Ubuntu 16.04 Xenial Xerus, Ubuntu 15.10 Wily Werewolf, Ubuntu 14.04 Trusty Tahr, Linux Mint 17.x and Elementary OS 0.3 Freya systems.