The beta test site appears to have no Cancel buttons implemented. Once one chooses to start something, the only option is to Save whatever one has done. This is a serious problem, even for experienced posters who often add comments to things, but may be interrupted midstream or change their minds after they start writing.
In fact, when I started writing this, I was unclear whether I was sending a message or adding a post to a blog. I had no idea that I was starting my own Blog!