Implement Secure Input Field mode on macOS

* Fixes #4738
* Also fixes flaky handling of caps lock detection events

src/gui/PasswordWidget.cpp

@@ -32,12 +32,17 @@
 #include <QTimer>
 #include <QToolTip>
 
+#ifdef Q_OS_MACOS
+#include <Carbon/Carbon.h>
+#endif
+
 PasswordWidget::PasswordWidget(QWidget* parent)
     : QWidget(parent)
     , m_ui(new Ui::PasswordWidget())
 {
     m_ui->setupUi(this);
     setFocusProxy(m_ui->passwordEdit);
+    m_ui->passwordEdit->installEventFilter(this);
 
     const QIcon errorIcon = icons()->icon("dialog-error");
     m_errorAction = m_ui->passwordEdit->addAction(errorIcon, QLineEdit::TrailingPosition);
@@ -223,14 +228,23 @@ void PasswordWidget::updateRepeatStatus()
     }
 }
 
-bool PasswordWidget::event(QEvent* event)
+bool PasswordWidget::eventFilter(QObject* watched, QEvent* event)
 {
-    if (isVisible()
-        && (event->type() == QEvent::KeyPress || event->type() == QEvent::KeyRelease
-            || event->type() == QEvent::FocusIn)) {
-        checkCapslockState();
+    if (watched == m_ui->passwordEdit) {
+        auto type = event->type();
+        if (isVisible() && (type == QEvent::KeyPress || type == QEvent::KeyRelease || type == QEvent::FocusIn)) {
+            checkCapslockState();
+        }
+#ifdef Q_OS_MACOS
+        if (type == QEvent::FocusIn) {
+            EnableSecureEventInput();
+        } else if (type == QEvent::FocusOut) {
+            DisableSecureEventInput();
+        }
+#endif
     }
-    return QWidget::event(event);
+    // Continue with normal operations
+    return false;
 }
 
 void PasswordWidget::checkCapslockState()
@@ -306,4 +320,4 @@ void PasswordWidget::updatePasswordStrength(const QString& password)
 
         break;
     }
-}
+}

src/gui/PasswordWidget.h

@@ -44,6 +44,8 @@ class PasswordWidget : public QWidget
     bool isPasswordVisible() const;
     QString text();
 
+    bool eventFilter(QObject* watched, QEvent* event) override;
+
 signals:
     void textChanged(QString text);
 
@@ -57,9 +59,6 @@ public slots:
     void setEchoMode(QLineEdit::EchoMode mode);
     void setClearButtonEnabled(bool enabled);
 
-protected:
-    bool event(QEvent* event) override;
-
 private slots:
     void popupPasswordGenerator();
     void updateRepeatStatus();