The new version of Thunderbird opens a window when an event in the calendar is opened (double clicked). Then I have to choose to edit it. This introduces an extra step in the process, apparently for no good reason. Why open a window? What can you do with it? It's a useless step. I open several events per day and it has become annoying, enough so that I am considering a change in applications. Please, get rid of that extra step. Also, it took me 15 minutes to determine how to leave a message.