As I build out templates, I'm finding that I'm very concerned about exactitude in the margins, particularly for things like framed prints where being off by 1/8" of an inch will short a print and make a white edge stick out like a sore thumb against a white mat. An older software suite I used to use had a similar ability to make your own templates (though not propagate them to the end user online - S+'s great innovation), and that software could recognize an alpha channel in a layer, which the software then interpreted as draggable. That software wasn't sophisticated enough to handle layers on the z axis, so you had to have at least a single pixel separating images to give the impression of depth in your designs, but if Stratus could pick out the draggable areas for each layer and then stack them, so much the better. I'm not sure about alpha channels and .png files, but perhaps some strange color like green screen could be used in a .png to signal a drop area if nothing else. The end to be achieved: I could rest easy knowing my boundaries were perfectly square, flush, etc. because I made it in Photoshop. I just can't trust it's close enough in the template builder for the most demanding production, and I don't have the resources to check it at scale manually.