Picture tubes are a feature that is apparently unique to PaintShop Pro. I am not sure at which version they started using tubes, but I know for a fact that version 4 had them, so it is definitely not new. For anyone who is not familiar with the basics of what picture tubes are, think of a roll of stickers: you can have a roll with all identical stickers, or a roll with several different stickers. Unlike brushes, the picture tubes are colored images by themselves, and you cannot change that, just like a sticker would have its own colors.
