As long as the sensor hasn't been passed the main window doesn't show any laps. After the first crossing there's a 0, after the second one a 1 and so on.
This is similar for the zoom window. But there's one exception. As long as the sensor hasn't detected anything a "-1" is displayed. I know this is only a minor thing and not really a bug. But many driver considered this a bit - don't know how to express best in English - maybe ugly.
Perhaps it's possible to display there nothing as it is done in the main window instead of showing a "-1" ... ?
I know - this is low priority ...