I’ve talked about the “preserve corners” feature previously on the blog, in the context of resizing an image button. That’s the typical use case, but there are some other cool things you can do with the feature when you’re working with screenshots of various other UI elements. Here’s a great one for when you want to insert an additional element into a form or dialog to quickly mock up a proposed change:
I’m selecting a thin horizontal slice of my dialog screenshot as the “center” portion and designating the rest—nearly the entire image—as the “edges”. This means that most of the image won’t resize at all when I make it taller, but the center slice I picked will stretch nicely. It’s doing all the stretching so the rest of the image doesn’t have to! If only this feature could come with me to yoga class … .