Markie is a wysiwyg editor for the markdown syntax written entirely in python with html preview of your own css.
Edit markdown in a left panel (didn't implement "select all" i just found out lol)
Preview the generated html in either a plain html renderer (no css) or
Preview the generated html in the iexplorer (windows only) using css
Allows you to select the "theme" (meaning more or less the css) to use for generation of the page More Info »
Either store the html only or the complete page (including css etc..)
Themes can easily be created by yourself. (just hava a look at the themes directory)
Allows you to move the preview panes so that you have all three views at once available