T3 Framework is one of Joomla! template frameworks. It features responsive design, powerful customization options and MegaMenu system.
It's a good framework, however, no system is free from bugs. In case with T3 you may occasionally encounter a situation where changes you are doing in MegaMenu Editor do not appear on the site. This is caused by corrupted template's JSON settings string.
To fix it, you need to access #__template_styles table of your Joomla! database, either with phpMyAdmin or by manually editing SQL dump.
The approach described here requires some basic knowledge of JSON & SQL. It may not be useful for beginners.
Modifying templates that are shipped with Joomla! core such as isis (or any other template) is not a good idea. Any upcoming update may overwrite your changes.
The best approach is to add a custom module to backend:
Mar 25, 2015: This article is back online, updated with the latest changes to Joomla! 3.4
Whatever you are developing - a complex application that consists of several extensions, a component or just a plugin for Joomla, you may encounter a situation when you need to add new editor button with your functionality. I faced this problem recently, and found that there's not so much information on the Web concerning this topic, at least in English. There are some fragments of necessary information, but not the complete step-by-step procedure. So I've decided to write this tutorial.