I often find myself wanting a border on only part of a rectangle - maybe just on the left and right side, or no border on the top, or only a border on the bottom. Currently the only option for a border is around the entire rectangle. You can work around this by building the border yourself with lines, or covering up part of the border with another rectangle, but those solutions are clunky at best.
I know the Microsoft Office products all have a dropdown when you click on the border button allowing you various choices of border styles. That's really what I would like to see in ForeUI!