Scrollers start at a random offset (timer % <length> basically). So if you present an alert with a long string in a scroller, you don't get to see the beginning of the sentence until it has finished scrolling to the end.
What I would expect: User sticks in USB dongle, unit recognises it and starts downloading the firmware off it, and presents the user with an alert on what it is doing on the 20x2 LCD. However, the user sees a partial message while waiting for the message to appear to confirm the download.
It would require an extra field in the widget struct. I'd be more than happy to come up with a patch for this if this is considered a good change.