[@netweb Keymaster 12 years, 4 months ago]

It is not a bug, we removed the default behaviour to have both editors enabled by default in 2.3.1, switching between editor types would more often than not change the content of the users topics or replies.

Now that TinyMCE v4 has shipped with WordPress v3.9.x once we have a few more architectural fixes in bbPress we can take another look, it is far from a small bug, quite complex to be honest.