C code analysis tool wanted

[Sean S. Safron]

I am looking for some C code analysis tools that will allow users to more
easily understand a C program's structure and flow.  

I have looked at the standard UNIX tool, cflow, and it does not completely
meet my needs.  I would like to find some kind of graphical front end to
cflow that would run in X-Windows and show a tree structure of the function
calls in a C program.

Another tool that I have used is C-Scope from AT&T.  This tool allows the 
user to find out things like which functions call which other functions.
This allows one to check the flow of a C program rather quickly, however, 
its limitation is that it does not show more than one level of function 
calls at a time.  The user must step through each level one by one to get
down to the lowest level functions.  I am looking for either an extension
to C-Scope or something similar that allows a user to browse the full tree
of function calls more easily.
 
Finally, if there are any other C code analysis tools that anyone has found
useful, please let me know.

--
 Sean S. Safron  IBM Corp.                    uunet!ibmps2!aix!safron 
"Any sufficiently advanced technology is indistinguishable from magic."