Light Table is a new IDE with a number of innovative features.

It can be used to edit Markdown very nicely. Because Light Table is a webapp at heart (it is written in Clojurescript) it will give you a live watch window next to the editor window, with no rendering or update lag.

Below are the steps I used to achieve this.

  1. Disable auto-complete. You will probably want to turn off auto-complete when editing Markdown. To do this open user behaviours and stick in:
      [:editor.markdown :-lt.plugins.auto-complete/auto-show-on-input]
    
  2. Add in plugins. Hit Ctrl-Space and search for Plugins: Show plugin manager; hit this and you can easily add plugins. I added the Vim and Markdown plugins. To enable vim key bindings in user.behaviors (which you can find by searching Settings: User behaviors you need to add:
      [:editor :lt.plugins.vim/activate-vim]
    
  3. To add a Markdown watch window for live rendering, search Markdown: Watch this editor for changes

  4. Once the watch window comes up in a new tab, simply right click on the tab and select Move editor to new tabset

Note: Light Table requires Java; I found the easiest way to install in OS X Yosemite was to use brew cask (brew cask install java).