I see that `legacy` means `P2PKH` in both command line options and RPC help info:
```
-addresstype
What type of addresses to use ("legacy", "p2sh-segwit", or "bech32", default: "p2sh-segwit") 
```
```
getnewaddress ( "label" "address_type" )
...
2. address_type    (string, optional, default=set by -addresstype) The address type to use. Options are "legacy", "p2sh-segwit", and "bech32".
...
```

The useLegacyAddress checkbox describes itself as “Generate legacy address” - however, it actually makes the wallet GUI generate “p2sh-segwit” address for the user if it's checked.
{
    if (!selectedRow().isValid()) {
        return;
    }
    contextMenu->exec(QCursor::pos());
}
void ReceiveCoinsDialog::copyURI()
{
    QModelIndex sel = selectedRow();
    if (!sel.isValid()) {
        return;
    }
    const RecentRequestsTableModel * const submodel = model->getRecentRequestsTableModel();
    const QString uri = GUIUtil::formatBitcoinURI(submodel->entry(sel.row()).recipient);
    GUIUtil::setClipboard(uri);
}
void ReceiveCoinsDialog::copyLabel()
{
    copyColumnToClipboard(RecentRequestsTableModel::Label);
}
void ReceiveCoinsDialog::copyMessage()
{
    copyColumnToClipboard(RecentRequestsTableModel::Message);
}
void ReceiveCoinsDialog::copyAmount()
{
    copyColumnToClipboard(RecentRequestsTableModel::Amount);
}