void EventRemove(ref EventHandler <WindowEventArgs> handler, EventHandler <WindowEventArgs> user,
EnumWindowEvent @event)
{
lock (_hooksDictionary)
{
if (handler != null && handler - user == null)
{
if (!DllUser32.UnhookWinEvent(_hooksDictionary[@event]))
{
throw new Win32Exception();
}
bool existed = _hooksDictionary.Remove(@event);
Debug.Assert(existed);
}
handler -= user;
}
}
