Some people, myself included, thought that buttons to adjust the indentation of code blocks would be useful, since apparently such buttons in all likelihood won't be implemented offically i tried to add this functionality via JavaScript.
The script can be found on GitHub (Source).
The direct link should (prompt for confirmation &) install the script if the browser supports it (i don't know about other browsers but Chrome has some native support and in Firefox you should install the Greasemonkey addon).
Feel free to contribute to and improve* the script, it could do with a more extensive list of includes as it only runs on StackOverflow (and Meta) for now. Another thing that is missing is the automatic preview update, i do not know how to trigger it via code, it should be called after the indentations are executed.
Edits:
- Script now supports the "new" dynamically added inline editors.
*Two weeks ago i pretty much used JavaScript for the first time, the code is likely to be crap.