As you may or may not know, Komodo is based on Mozilla, same as Firefox. You might even say Komodo is based on Firefox. As you may also know, Firefox has a very flexible addon system. In fact, there are very few areas of Firefox that you cannot customize with an Addon. People have written entire applications inside of Firefox, and entire applications have been written on top of Firefox's foundation--Thunderbird, Selenium, Postbox and of course Komodo, to name a few.