Compose email in Gmail and edit HTML: is there a browser addon for this?

Question

Many WYSIWYG editors allow two modes:

• easy mode (with icons for bold, italic, etc.),
• but also a mode in which you can edit directly the HTML code.

Is there a way to enable this in Gmail too, with a browser extension for Chrome or Firefox that would add such a "HTML edit" panel? i.e. let the user modify the HTML codes for email.

Example of such HTML editor (WordPress):

Answer 1

I now use the Markdown here browser extension for this.

Of course this is not HTML, as mentioned in my question, but it allows the emails to be edited "with code" (Markdown) and do CTRL+ALT+M to have the rendered output.

That's the closest solution I found to what I was looking for. Finally Markdown is even better than editing HTML directly (If you are active on StackExchange, you're probably already convinced by this ;)).