The latest version of tonight includes an interesting new approach to preview a message. This is applicable so far at the messages level. The private message will benefit of that new behavior within a few days as well. The new preview allows to view with DHTML the message at the bottom of the one being written. So, basically, we can update the message as desired and click as often as we want to update the preview area.
This new version also includes a completion the message options. So, once a message is saved, the flickering reported recently should not longer apply.
The new version also includes some minor enhancements when updating a message and some improvements in the response time for several options.