Function drmgr_register_low_on_memory_event_ex 

pub unsafe extern "C" fn drmgr_register_low_on_memory_event_ex(
    func: Option<unsafe extern "C" fn()>,
    priority: *mut drmgr_priority_t,
) -> bool_

Registers a callback function \p func for the low-on-memory event just like drmgr_register_low_on_memory_event(), but the callback is prioritised according to \p priority. \return whether successful.