file: roundcubemail-0.1-rc1.1.tar /roundcubemail-0.1-rc1/program/js/app.js
line 1683: if ((input_message.value=='')&&(tinyMCE.getContent()=='')) I don't have tinymce installed, the variable tinyMCE cause a javascript error when send message without body.
Should it be if ((input_message.value=='')&&((!tinyMCE) true : tinyMCE.getContent()==''))
List info: http://lists.roundcube.net/dev/