I'm trying to add callback functions to a Gtk.Builder using Gtk.Builder.add_callback_symbol. I tried to pass a python function to it, but that does not work. Documentation says I need to pass a GObject.Callback instead, so I tried to cast one by calling GObject.Callback(myfunc) but got a NotImplementedError. The C-Documentation on GCallback says I need to use something called G_CALLBACK to typecast. But there does not seem to be any reference to this in PyGObject and I'm lost at that point.
I would like to say beforehand, that I know callback can be also added by using 'Gtk.Builder.connect_signals', but that's not the question here.
The GObject.Callback function is just there for documentation purposes atm. You can just pass a function matching the signature of the callback type, in this case a function which doesn't take any arguments and has no return value.