As a general rule, there still remains not a single HTML editor that handles the HTML source exactly the way some of us "power users" will expect. Something will undoubtedly get changed or removed. A large number of these instances are related to the syntax updating faster than the various online editors. However, the biggest reason is that most of these editors are trying to protect the rest of the users that are using the same tool.
So, as Timo suggested, if you want full and unbridled control over your HTML, you really should use any structured content solution out there. Lucky for us all, the two most popular ones are both open-source and listed for you below. 😎