Maybe they have some purpose, but it isn't immediately obvious. I tried Tree & List mode, they're never populated.

![image](https://user-images.githubusercontent.com/13134193/33488849-04a2c8a6-d6ed-11e7-85c3-5c05f1ec5346.png)

* Bitcoin-Qt 0.15.1 for Ubuntu 16.04 x64 (from http://ppa.launchpad.net/bitcoin/bitcoin/ubuntu xenial/main amd64)

Note: I just noticed I'm *not* seeing this on Ubuntu 17.10 x64 with 0.15.1 downloaded from bitcoincore.org. 

![image](https://user-images.githubusercontent.com/13134193/33491553-9584dc62-d6f5-11e7-9ba7-e074e0e36151.png)


nQuantity++;
        
        nAmount += out.txout.nValue;
        
        CTxDestination address;
        int witnessversion = 0;
        std::vector<unsigned char> witnessprogram;
        if (out.txout.scriptPubKey.IsWitnessProgram(witnessversion, witnessprogram))
        {
            nBytesInputs += (32 + 4 + 1 + (107 / WITNESS_SCALE_FACTOR) + 4);
            fWitness = true;
        }
        else if(ExtractDestination(out.txout.scriptPubKey, address))
        {
            CPubKey pubkey;
            CKeyID *keyid = boost::get<CKeyID>(&address);
            if (keyid && model->wallet().getPubKey(*keyid, pubkey))
            {
                nBytesInputs += (pubkey.IsCompressed() ? 148 : 180);
            }
            else
                nBytesInputs += 148; 
        }
        else nBytesInputs += 148;
    }
    
    if (nQuantity > 0)
    {
        
        nBytes = nBytesInputs + ((CoinControlDialog::payAmounts.size() > 0 ? CoinControlDialog::payAmounts.size() + 1 : 2) * 34) + 10;