add_callback_symbol
Description:
Adds the callback_symbol to the scope of builder under the given callback_name.
Using this function overrides the behavior of [method@Gtk.Builder.create_closure] for any callback symbols that are added. Using this method allows for better encapsulation as it does not require that callback symbols be declared in the global namespace.
Parameters:
| this |
a `GtkBuilderCScope` |
| callback_name |
The name of the callback, as expected in the XML |
| callback_symbol |
The callback pointer |