1. At present, the maximum number of files has to be set in BOTH include 
files, FileList.h and FileListP.h.  This does not fit into the philosophy
shown in other FWF widgets, but is a result of the fact that this constant
is used both by internal and external routines.  It's probably possible to
get around this requirement by dynamically allocating each new path and 
file pointer for the list (as well as the strings themselves).

2. Unhighlight any selected item in the file list if an item in the selected
list is highlighted.

3. Optional: Find a more elegant way to notify the user of a redundant file
and path selection than printing a message to stderr.

4. Optional: Draw a line separating the selected list part of the GUI from
the rest of it.

