There are some upcoming changes in the codebase you need to know about. Namely, I'm nearing the end of the first stage of C++ification of SPObject: conversion from GObject to sigc++ signals.
This means that instead of this kind of thing to connect to "release" or "modified" on an SPObject:
g_signal_disconnect_...(G_OBJECT(object), ..., widget); ... g_signal_connect(G_OBJECT(object), "release", G_CALLBACK(&foo), widget);
...you'll need to do something like this:
widget->release_connection.disconnect(); ... widget->release_connection = object->connectRelease(sigc::bind<1>(sigc::ptr_fun(&foo), widget));
I'll be glad to give you any assistance you need to convert your code to use the new API, which I've made available beforehand to ease the transition. The old API hasn't gone away yet, but it will on Saturday.
-mental