Easy way to align image with edges of slide?

I'm finally making the switch from PowerPoint to Keynote...

I often need to insert a long sequence of images into slides, all at their maximum size with their edges aligned precisely with the edges of the slide. In PP this is easy -- as you pull the corner to enlarge or reduce an image, it will automatically "snap to" the slide edge.

In Keynote it doesn't seem to happen, at least as a default behavior. Is there a simple way set this up?

I can put alignment guides at the right-hand and bottom edges, but they still don't appear to "grab" images the way PP does.

Thanks!