Callback delegate, invoked when a new file descriptor should be added to the set of file descriptors monitored for events.
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- fd (Int32)
- The new file descriptor.
- events (Int16)
- Events to monitor for, see PollfdItem for a description.
- user_data (IntPtr)
- User data pointer specified in SetPollfdNotifiers(MonoUsbSessionHandle, PollfdAddedDelegate, PollfdRemovedDelegate, IntPtr) call.