Rick Brewster, lets supose that you click with the magic on the left black colum of this image:
If you have contiguous pixels enable, you will only have the left colum selected because the left and right colums aren't contiguous. However, if it's disabled, you will select both left and right black colums.
Could you please add it to the next versions? Photoshop has it and I missing it on Paint.net. It's very useful. :wink: