Text metrics

Hi!

I'm trying to render a directory tree, which consists of an icon (left) 
with some text (right), like this:

ICON Direcoryname
  [-] ICON Directoryname
       |   ICON Directoryname
  [+] ICON Directoryname

Now I have the following problem:
How can I place the directory name on the right height? Each directory 
name is a text-element itself, but I couldn't find any way to retrieve 
the maximum height of the used font and the relative position of the 
baseline in it. Is there a good way to retrieve that information?

Thanks in advance
Bernd Fuhrmann