gtk4: objprop_setup_widget() creating checkbutton later tried to use as togglebutton
gtk4-client objprop_setup_widget() does "button = gtk_check_button_new();" when the button is later assumed to be GtkToggleButton.
gtk4-client objprop_setup_widget() does "button = gtk_check_button_new();" when the button is later assumed to be GtkToggleButton.