Terrible UI in this Thunderbird feature

While Thunderbird (ver 2.0.0.23) has Junk filter that allegedly using Bayesian technique, its operations are not as robust as others, particularly in the failure to explain why a message is classified as spam.

The other most annoying feature is represented by this dialog box with total neglect of good user interface design:
Now any normal users, other than the developer who wrote this, will instinctively press the 'Clear log' button to clear the log being shown. Not really! This is not how it is supposed to work.

You have to first select the log content, such as Ctrl-A, and then press the 'Clear log' button. I am puzzled why that button is enabled when no content is selected? Doing so with guide the user to use this properly.

As for the content of the log, it is as useful as saying nothing! I would like to see a spam rating much like that presented by SpamBayes.