In the GObject Reference Manual, it denotes that for a function:
g_signal_connect(instance, detailed_signal, c_handler, data)
A detailed_signal string parameter of form "signal-name::detail" is desired. My initial understanding of that is that there are predefined signal details to pass in. If that is the case, where can I find a list of these? If not, then what exactly does it mean, as the manual doesn't make that too terribly obvious.
The ::detail part of the signal name is optional. If a signal takes a detail parameter, then it will say so in the signal's documentation. Otherwise you can ignore it.
The only signal that I'm aware of that actually uses a detail parameter, is the notify signal of GObject. The notify signal without a detail fires whenever any property changes on the object, so it's fairly useless. But if you connect to the notify::visible signal, then it will fire whenever the object's visible property changes.