[plt-scheme] stepper for full language

Any idea how hard it would be to add to DrScheme a stepper of some kind
that works with the Textual or R5RS language, rather than just the
teaching languages?

The stepper need not expand macros.  Something simply like the
source-based EDebug stepper in GNU Emacs 21 would be a godsend.

With EDebug, you use a editor command to instrument a particular
procedure in your source code window for debugging.  When the procedure
is evaluated, the source code pops up in a window.  As each sexp is
evaluated recursively, the sexp is highlighted in the source and the
value is displayed in the Emacs echo area.  Command keys let you step
through the execution, skip subexpressions, etc.

I realize an EDebug-like stepper is harder to implement for Scheme than
for less-powerful languages like Elisp.  But perhaps most of the
necessary support is already implemented in DrScheme?

-- 
                                             http://www.neilvandyke.org/