Double Border
This tutorial will show you how to add a double border, thier might be other ways and if I find them I will post them, but this is the first.
and
, Draw out a box about 1 pixels distance away (on the inside of course) from the first border. You can change the distance to whatever you like.
click on the area between the TWO borders so it's selected like this:
and fill it with the color of your choice, so you should have something like this now.