HOW TO USE:
You can code and design blogspot widgets using this HTML editor. Simply add your JavaScript, HTML and CSS code to the left panel. Hit the "Preview" button too see your code in action on the right panel.
I personally use it for developing blogger widgets and plugins. Its the most handy UI tool to play with!
Good News:
In event of accidental browser crash or page refresh, your data is reserved and not lost. So you can code easily without worrying about loosing your code. :)