As an ex Photoshop user, there is a facility missing from PDN (or at least I can't find it!)
In Photoshop there was a tool which allowed me to type in a width and a height and a unit of measurement, for instance, 6, 4 and inches which would give me a 6x4 ratio image. I could then drag a rectangle across my image, and the crop box would remain in the correct ratio, making for very easy cropping when preparing images to be printed.
Is there a similar way in PDN to achieve this?