RISC OS Specific notes:
  To use include "sigc:signal_system.h" in your source. 
   (Use <> if you really want).

  Use "-Lsigc: -lsigc" in the command line to link.

If your filetypes aren't set properly, set 'stype,feb' to type Obey (FEB) 
and run it.

A port of the libsigc++ was done for RISC OS by Ainsley Pereira.  
He maintains a page on how to port the source at 
http://www.snowplains.org/~marble/libsigc++/

To build a RISC OS distribution on a unix machine...
 - unpack the unix distribution
 - configure
 - make dist
 - make riscos-dist