A user reported to me that they are unable to create a PSBT with a legacy watchonly wallet when they use the GUI. They get an error "The amount exceeds your balance".

I think the issue is that the GUI will retrieve the wallet's balance via `AvailableCoins` before calling `CreateTransaction`. This call to `AvailableCoins` is resulting in fewer coins being returned with recent changes to how `AvailableCoins` works, particularly with additional filtering of spendable coins and preset coins.

***

Note that this does not effect descriptor wallets. A workaround for this issue is to switch to using descriptor wallets. An existing legacy wallet can be turned into a descriptor wallet using the `migratewallet` RPC. However many watchonly legacy wallets are likely the result of importing descriptors via `importmulti`. For such wallets, I recommend creating a new descriptor wallet and re-importing the descriptors.
{
    auto dlg = new CoinControlDialog(*m_coin_control, model, platformStyle);
    connect(dlg, &QDialog::finished, this, &SendCoinsDialog::coinControlUpdateLabels);
    GUIUtil::ShowModalDialogAsynchronously(dlg);
}
: checkbox custom change address
void SendCoinsDialog::coinControlChangeChecked(int state)
{
    if (state == Qt::Unchecked)
    {
        m_coin_control->destChange = CNoDestination();
        ui->labelCoinControlChangeLabel->clear();
    }
    else
        // 
        coinControlChangeEdited(ui->lineEditCoinControlChange->text());
    ui->lineEditCoinControlChange->setEnabled((state == Qt::Checked));
}
: custom change address changed