The plan for rolling out Komodo 7 is to bring on a wave of new functionality with each new alpha. This time the main difference is a revamp in the way we do as-you-type syntax checking.
Revisiting syntax checking
We've found there are two other HTML libraries written as Perl modules (HTML::Tidy and HTML::Lint) that sometimes do better HTML checking than Tidy, so you now have the option of using those. If you've moved to HTML5, you can check it with Komodo's built-in html5lib instead.
Roll your own
Finally, the new syntax checking system is fully extensible. The three parts to add support for a new language are: UDL to describe the language, an XPCOM library to determine how the checking works, and a Mozilla extension to add new preference pages. If you just want to add support for a new checker for an existing language, you can do that with a simple Mozilla extension.
Updated Mozilla under the hood
Additionally there have been several bug fixes since the last alpha, particularly in the new sync and collaboration modules.