I’ve recently released ghostwriter, which is a new Markdown editor for Windows and Linux. You can view its website here: http://wereturtle.github.io/ghostwriter.
If you install the latest Pandoc (which has CommonMark support) or cmark, the application will automatically detect them so long their locations are in your system’s PATH environment variable. Once detected, the application will offer them (including Pandoc’s CommonMark rendering) as options to render a live HTML preview, or to export to other file formats. It can likewise detect MultiMarkdown, Discount, and older versions of Pandoc.
When the CommonMark spec reaches version 1.0.0, I hope to have the syntax highlighting favor CommonMark more. Right now, it’s rather loose to accommodate different Markdown flavors. Also, Sundown is currently built into the application as a default, and I hope to do the same with cmark once I figure out how to integrate cmake into the Qt build process.
Please take it for a spin! It’s open source (i.e. FREE). It currently only has a Windows setup.exe, but I am working toward deb and RPM packages. Hopefully I’ll make friends with a Debian maintainer soon. In the meantime, if you are on Linux, just follow the README.md instructions to build on the application’s GitHub page. You’ll need the Qt 4.8 or 5.2+ libraries installed, including the one for WebKit.