I'm sorry I can't explain, but it's not important. Try going to Settings --> Format; There are the W ratio and H ratio input boxes that match the "Scale" boxes in Resize Track. In this way we have to calculate the ratio we want (40/17 or 2.35 or W/ratio =H; etc). As you indicated. But in Format there is an additional input box called "Aspect ratio" with the "Auto" button next to it. This box lets you choose the aspect ratio directly: 4:3 - 16:9 - 2.35 - etc. I would also like this box in "Resize Track" (and also in "Resources --> Info --> Resize"). It's one more thing, since it's trite to do the calculation on your own, but the concept of aspect ratio is important and not trivial, especially for the beginners. Providing a direct and clear input box seems to me a good idea. But I repeat: it's not important at all.