I took a look at libsidc++ and found very interresting the way of blocking/unblocking connections. I added some small modifications in boost::signals lib in order to have this functionality (2 patches in attachment to apply at the parent of the boost_1_32_0 distrib). Only the interface of connection has changed (3 new methods), and I added a boolean flag in basic_connection struct. Also, a functor is_callable was added in the file connection.hpp, in replacement of the is_disconnected functor (used in the class slot_call_iterator). So, my questions are: 1) is it interresting/useful to incorporate it (for me, yes of course)? 2) is it a safe implementation? You can test it like that: \code void fct1(int) ; void fct2(int) ; MySignal sig ; boost::signals::connection conn = sig.connect(&fct1) ; sig(10) ; // call fct1 and fct2 conn.block() ; sig(20) ; // call only fct2 conn.unblock() ; sig(30) ; // call fct1 and fct2 \endcode --Frantz