+ class CollapsibleGroupBox, yet unused

GUI/View/Widget/GroupBoxes.cpp

@@ -44,6 +44,56 @@ HeinzGroupBox::HeinzGroupBox(const QString& title, QWidget* parent)
     setLayout(layout);
 }
 
+//  ************************************************************************************************
+//  class CollapsibleGroupBox
+//  ************************************************************************************************
+
+CollapsibleGroupBox::CollapsibleGroupBox(const QString& title, QWidget* parent, bool& expanded)
+    : QWidget(parent)
+{
+    auto* m_toggleButton = new QToolButton(this);
+    m_toggleButton->setObjectName("GroupBoxToggler");
+    m_toggleButton->setToolButtonStyle(Qt::ToolButtonTextBesideIcon);
+    m_toggleButton->setCheckable(true);
+    m_toggleButton->setText(title);
+    m_toggleButton->setArrowType(Qt::ArrowType::DownArrow);
+    m_toggleButton->setChecked(true);
+    m_toggleButton->setSizePolicy(QSizePolicy::Minimum, QSizePolicy::MinimumExpanding);
+
+    auto* m_titleLayout = new QHBoxLayout;
+    m_titleLayout->setContentsMargins(0, 0, 3, 0);
+    m_titleLayout->setSpacing(3);
+    m_titleLayout->setAlignment(Qt::AlignVCenter);
+    m_titleLayout->addWidget(m_toggleButton);
+
+    auto* m_titleWidget = new QWidget(this);
+    m_titleWidget->setObjectName("GroupBoxTitleWidget");
+    m_titleWidget->setAttribute(Qt::WA_StyledBackground, true);
+    m_titleWidget->setLayout(m_titleLayout);
+
+    m_body = new QWidget(this);
+    m_body->setObjectName("ContentArea"); // stylesheet -> transparent background
+    m_body->setVisible(expanded);
+
+    auto* layout = new QVBoxLayout;
+    layout->setSpacing(0);
+    layout->setContentsMargins(0, 0, 0, 0);
+    layout->setMenuBar(m_titleWidget);
+    layout->addWidget(m_body);
+
+    setLayout(layout);
+
+    connect(
+        m_toggleButton, &QAbstractButton::clicked,
+        [this, &expanded](bool checked) {
+            this->m_toggleButton->setArrowType(checked ? Qt::ArrowType::DownArrow
+                                                 : Qt::ArrowType::RightArrow);
+
+            this->m_body->setVisible(checked);
+	    expanded = checked;
+        });
+}
+
 //  ************************************************************************************************
 //  class GroupBoxCollapser
 //  ************************************************************************************************

GUI/View/Widget/GroupBoxes.h

@@ -22,7 +22,7 @@ class QAction;
 class QHBoxLayout;
 class QToolButton;
 
-//! A QGroupBox with given title and layout, and some standard styling.
+//! A group box with given title and layout, and some standard styling.
 
 class HeinzGroupBox : public QWidget {
 public:
@@ -33,6 +33,20 @@ private:
     QWidget* m_body;
 };
 
+//! A group box that can be expanded or collapsed, according to external boolean flag 'expanded'.
+
+class CollapsibleGroupBox : public QWidget {
+public:
+    CollapsibleGroupBox(const QString& title, QWidget* parent, bool& expanded);
+    QWidget* body() { return m_body; }
+
+private:
+    QWidget* m_titleWidget;      //!< widget used to present the new groupbox title
+    QHBoxLayout* m_titleLayout;  //!< layout in the title widget
+    QToolButton* m_toggleButton; //!< button to toggle between collapsed/expanded
+    QWidget* m_body;
+};
+
 
 //! Add-on to group boxes to make them collapsible.
 //!