Just installed latest 0.4 version of Roundcube and applied the steps mentioned at TinyMCE:Configuration/force br newlines - Moxiecode Documentation Wiki (http://wiki.moxiecode.com/index.php/TinyMCE:Configuration/force_br_newlines) to have a normal line break after hitting enter.
This works fine while composing new HTML emails, but when I reply to an HTML mail, the behaviour is unchanged: hitting enter results in a new paragraph instead of a new line.
Any advice?