[gui] send: show watch-only balance in send screen

Author: Sjors

src/qt/forms/sendcoinsdialog.ui

@@ -1190,7 +1190,7 @@ Note:  Since the fee is calculated on a per-byte basis, a fee of "100 satoshis p
         <number>3</number>
        </property>
        <item>
-        <widget class="QLabel" name="label">
+        <widget class="QLabel" name="labelBalanceName">
          <property name="sizePolicy">
           <sizepolicy hsizetype="Preferred" vsizetype="Fixed">
            <horstretch>0</horstretch>

src/qt/sendcoinsdialog.cpp

@@ -562,7 +562,12 @@ void SendCoinsDialog::setBalance(const interfaces::WalletBalances& balances)
 {
     if(model && model->getOptionsModel())
     {
-        ui->labelBalance->setText(BitcoinUnits::formatWithUnit(model->getOptionsModel()->getDisplayUnit(), balances.balance));
+        CAmount balance = balances.balance;
+        if (model->privateKeysDisabled()) {
+            balance = balances.watch_only_balance;
+            ui->labelBalanceName->setText(tr("Watch-only balance:"));
+        }
+        ui->labelBalance->setText(BitcoinUnits::formatWithUnit(model->getOptionsModel()->getDisplayUnit(), balance));
     }
 }