Parses a resource file containing a UI definition and merges it with the current contents of this.
This function is useful if you need to call [method@Gtk.Builder.set_current_object] to add user data to callbacks before loading GtkBuilder UI. Otherwise, you probably want [ctor@Gtk.Builder.new_from_resource] instead.
If an error occurs, 0 will be returned and throws will be assigned a `GError` from the gtk_builder_error, g_markup_error or g_resource_error domain.
It’s not really reasonable to attempt to handle failures of this call. The only reasonable thing to do when an error is detected is to call error.
the path of the resource file to parse
true on success, false if an error occurred