Function gtk_sys::gtk_buildable_custom_tag_start

pub unsafe extern "C" fn gtk_buildable_custom_tag_start(
    buildable: *mut GtkBuildable, 
    builder: *mut GtkBuilder, 
    child: *mut GObject, 
    tagname: *const c_char, 
    parser: *mut GMarkupParser, 
    data: *mut gpointer
) -> gboolean