I would love the ability to have the ability to adjust the image size relative to a specific window. For example, if I am editing images at 25% size and some images have different megapixels they would still fill the predetermined window size instead of getting larger or smaller as I progress. I prefer to have a lot of grey around my images in the develop modue, so it's distracting having the images change sizes so frequenty if say I'm working on a catalog of images from different cameras with different megapixels.
If anyone uses Photomechanic, you know what I'm talking about.