Disconnect the associated slot. If the slot was already disconnected, this function has no effect. This function blocks the calling thread pending completion of signals emitted on the signaler by any thread, even if the slot was disconnected prior to this call. Any signal emitted on the corresponding signaler that happens after this call to disconnect completes will not emit to the slot. Throws nothing. The behavior is undefined if this method is called from any slot. Note that it is unspecified if any signal emitted on the signaler that begins before this function completes will call the slot.