[boost] inter-thread signals

Hello, I'm working on a project using QT and boost and we have a requirements that certains signals should be handled inside main QT thread but raised in another thread. So i'm trying approach in the attached file. Basically i've created a SlotFuction which derives from boost::function and does inter-thread magic when needed. I'm not really (yet) boost guru so i would like to have some feedback. It is evident that this approach suffer of one problem: the event handler registration/invocation is not really thread safe, but i think this can be handled automatically by recent thread_safe_signals library. Thanks Vadim