Edit .md and .txt files with outlines & syntax highlighting.
Preview HTML.

Please see the website for information: http://www.winterwell.com/software/markdown-editor.php

Eclipse Marketplace entry: http://marketplace.eclipse.org/content/markdown-text-editor

There is also complementary Github Flavoured Markdown Viewer https://github.com/satyagraha/gfm_viewer

Main Editor class winterwell.markdown.editors.MarkdownEditor defined as

  <editor
        name="Markdown Editor"
        extensions="txt,md"
        icon="icons/notepad.gif"
        contributorClass="winterwell.markdown.editors.ActionBarContributor"
        class="winterwell.markdown.editors.MarkdownEditor"
        id="winterwell.markdown.editors.MarkdownEditor">
  </editor>

mvn package

then check site\target directory for update site archive markdown.editor.site-x.x.x.zip and p2 repository. Use Help -> Install New Software... -> Add... -> Archive to istall from .zip file.