As comment windows are small, widgetless windows, obviously, links that are posted in comments windows have to open in a new window. When I discovered that my target="new" attributes were being stripped out, I was completely befuddled, and I had to sit here for a half hour trying to figure out WTF was going on, until I eventually learned that I had to reconfigure the html sanitize feature. Even though MT is doing what it was designed to do, I have to consider this a bug. There is no reason why you would want the default setting to strip out target attributes from your comments. This default should be changed to include target attributes.