HTR:

1. Open a thread
2. Click on 'New message'
3. "Send message" button is disabled => OK
4. Type 'foo'
5. Type 'Ctrl + A' and then 'BACKSPACE' to remove your text
6. "Send message" button is enabled => KO
7. Click on "Send message" => the "foo" content of the post was saved !!! => KO

Same behavior for hte comment feature of the Document Module !

Discovered while testing WORKSPACES-168, so perhaps you should base your fix on its commits