Visualize whitespace and tab

Hello,

I want to write some examples about possible use of whitespace in source code. So I am looking for a way to visualize the use of tab and whitespace in source code listing.

Editors like Word or Notepad can display tabs as little arrows and spaces as little grey dots. I know, I can figure out the unicode code point of these characters, but I would prefer to use tab and space in <literallayout> and have fop displaying the arrow or the dot automagically.

I hope somebody has an idea how this can be achieved,

Thanks in advance,

Mario