Crop image to full page

When working with Bloom Comics, it would be helpful to have “Crop-to-full-page” button added to the “Image Toolbox”.

This feature would cause Bloom to overlay a target aspect ratio “result window” over top of the image and would then allow the user to “slide” the “result window” up and down or side to side in order to allow the user to obtain the best posible cropped image with the exact aspect ratio for the target page size, typically 16x9.