Hello! I'm making video tutorials and I'd like to find out the easiest way to make text subtitles atop a transparent black background with rounded corners. Like this:

» http://www.macobserver.com/tip/2006/12/growl_unplugged.jpg
» http://daringfireball.net/misc/2008/02/fastscripts-message-window-thumb.png

I know Vegas can do drop-shadowed text with the Text Media tool, but it looks like I'm going to need some layering to do the background.

Also, is there any way I can have background layers automatically track the position of the text and wrap around it? I like doing this with the glow effect but I'd like to extend this to the aforementioned Growl-like background.

Thanks very much in advance for the help!