Qt: Delay user confirmation of send

I made a subclass of QMessageBox that disables the send button in
exec() and starts a timer that calls a slot to re-enable it after a
configurable delay.

It also has a countdown in the send/yes button while it is disabled
to hint to the user why the send button is disabled (and that it is
actually supposed to be disabled).

src/qt/sendcoinsdialog.cpp

@@ -26,6 +26,9 @@
 #include <QScrollBar>
 #include <QSettings>
 #include <QTextDocument>
+#include <QTimer>
+
+#define SEND_CONFIRM_DELAY   3
 
 SendCoinsDialog::SendCoinsDialog(const PlatformStyle *platformStyle, QWidget *parent) :
     QDialog(parent),
@@ -311,10 +314,10 @@ void SendCoinsDialog::on_sendButton_clicked()
     questionString.append(QString("<span style='font-size:10pt;font-weight:normal;'><br />(=%2)</span>")
         .arg(alternativeUnits.join(" " + tr("or") + "<br />")));
 
-    QMessageBox::StandardButton retval = QMessageBox::question(this, tr("Confirm send coins"),
+    SendConfirmationDialog confirmationDialog(tr("Confirm send coins"),
-        questionString.arg(formatted.join("<br />")),
+        questionString.arg(formatted.join("<br />")), SEND_CONFIRM_DELAY, this);
-        QMessageBox::Yes | QMessageBox::Cancel,
+    confirmationDialog.exec();
-        QMessageBox::Cancel);
+    QMessageBox::StandardButton retval = (QMessageBox::StandardButton)confirmationDialog.result();
 
     if(retval != QMessageBox::Yes)
     {
@@ -828,3 +831,45 @@ void SendCoinsDialog::coinControlUpdateLabels()
         ui->labelCoinControlInsuffFunds->hide();
     }
 }
+
+SendConfirmationDialog::SendConfirmationDialog(const QString &title, const QString &text, int secDelay,
+    QWidget *parent) :
+    QMessageBox(QMessageBox::Question, title, text, QMessageBox::Yes | QMessageBox::Cancel, parent), secDelay(secDelay)
+{
+    setDefaultButton(QMessageBox::Cancel);
+    yesButton = button(QMessageBox::Yes);
+    updateYesButton();
+    connect(&countDownTimer, SIGNAL(timeout()), this, SLOT(countDown()));
+}
+
+int SendConfirmationDialog::exec()
+{
+    updateYesButton();
+    countDownTimer.start(1000);
+    return QMessageBox::exec();
+}
+
+void SendConfirmationDialog::countDown()
+{
+    secDelay--;
+    updateYesButton();
+
+    if(secDelay <= 0)
+    {
+        countDownTimer.stop();
+    }
+}
+
+void SendConfirmationDialog::updateYesButton()
+{
+    if(secDelay > 0)
+    {
+        yesButton->setEnabled(false);
+        yesButton->setText(tr("Yes") + " (" + QString::number(secDelay) + ")");
+    }
+    else
+    {
+        yesButton->setEnabled(true);
+        yesButton->setText(tr("Yes"));
+    }
+}

src/qt/sendcoinsdialog.h

@@ -8,7 +8,9 @@
 #include "walletmodel.h"
 
 #include <QDialog>
+#include <QMessageBox>
 #include <QString>
+#include <QTimer>
 
 class ClientModel;
 class OptionsModel;
@@ -100,4 +102,24 @@ Q_SIGNALS:
     void message(const QString &title, const QString &message, unsigned int style);
 };
 
+
+
+class SendConfirmationDialog : public QMessageBox
+{
+    Q_OBJECT
+
+public:
+    SendConfirmationDialog(const QString &title, const QString &text, int secDelay = 0, QWidget *parent = 0);
+    int exec();
+
+private Q_SLOTS:
+    void countDown();
+    void updateYesButton();
+
+private:
+    QAbstractButton *yesButton;
+    QTimer countDownTimer;
+    int secDelay;
+};
+
 #endif // BITCOIN_QT_SENDCOINSDIALOG_H