Curious. I have a Silverlight application where you can choose set margins for a piece of text. Thus you can choose set the margin on more than one side of the text (top, bottom, left, right). Currently, I just have a window that has a few blurry lines and hollow arrows on all for sides, similar to the Interface Builder on Xcode.
So far, none of my users have found that confusing, but I was wondering if there was a better method. All other applications I know of that set margins simply show a number box on all four sides, similar to Microsoft Word.