Drawing 9patch can turn into a nightmare easily. I would like to present the other side. The most common problem, to create draws wich are look well in portrait mode and landscape mode too.
Example One: Simple button
This is a just simple button, with a glowing effect. The 9patching wich I use here, keeps the button’s edges, so it keeps the rounded rectangle’s radius too. With 9patch, the content area of the button can be set easily.