Comment 7 for bug 1350973

The answer is in the lines 4781-4792:

bool ClientConnection::SendServerInput(BOOL enabled)
{
    rfbSetServerInputMsg sim;
    int len = 0;

    sim.type = rfbSetServerInput;
    sim.status = enabled;

    WriteExact((char*)&sim, sz_rfbSetServerInputMsg, rfbSetServerInput);

    return true;
}