Comment 1 for bug 10883

When composing mails in HTML, you can go to Options > Format and select the
format of the mail, i.e. you can go back to plain-text mode. So switching should
be possible, right?
Currently you cannot change from plain-text composing to HTML (when plain text
is default) since the menu item is not available then.
And the HTML -> plain text conversion is not existant for the user since all
styles (formatting) are kept until the message is send.

What would be useful when implementing this: selecting the account from compose
window ("From:" drop-down) should active the respective default composing mode
(HTML or plain text) for that account.