Hi!

It looks like Event's bool wait() method may do a disservice. It returns false if Event struct isn't initialized.

Maybe implement mandatory ctor or replace conditions like:

    if (!m_event)
        return false;

by asserts?

This call (sometimes?) silently doesn't do anything because uninitialized Event instance called:
https://github.com/dlang/druntime/blob/master/src/gc/impl/conservative/gc.d#L2788