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)


{
    sortColumn = column;
    sortOrder = order;
    ui->treeWidget->sortItems(column, order);
    ui->treeWidget->header()->setSortIndicator(sortColumn, sortOrder);
}
void CoinControlDialog::headerSectionClicked(int logicalIndex)
{
    if (logicalIndex == COLUMN_CHECKBOX) 
    {
        ui->treeWidget->header()->setSortIndicator(sortColumn, sortOrder);
    }
    else
    {
        if (sortColumn == logicalIndex)
            sortOrder = ((sortOrder == Qt::AscendingOrder) ? Qt::DescendingOrder : Qt::AscendingOrder);
        else
        {
            sortColumn = logicalIndex;
            sortOrder = ((sortColumn == COLUMN_LABEL || sortColumn == COLUMN_ADDRESS) ? Qt::AscendingOrder : Qt::DescendingOrder); 
        }
        sortView(sortColumn, sortOrder);
    }
}
void CoinControlDialog::radioTreeMode(bool checked)
{
    if (checked && model)
        updateView();
}
void CoinControlDialog::radioListMode(bool checked)