diff --git a/GUI/View/Widget/GroupBoxes.cpp b/GUI/View/Widget/GroupBoxes.cpp
index 6b2de2202ac709010abaf4388eed6cd086f1e0c8..17b33997723204f56e99dad4f602e36e88492ddd 100644
--- a/GUI/View/Widget/GroupBoxes.cpp
+++ b/GUI/View/Widget/GroupBoxes.cpp
@@ -119,103 +119,3 @@ void CollapsibleGroupBox::setExpanded(bool expanded)
     if (m_toggleButton->isChecked() != expanded)
         m_toggleButton->click();
 }
-
-//  ************************************************************************************************
-//  class GroupBoxCollapser
-//  ************************************************************************************************
-
-GroupBoxCollapser* GroupBoxCollapser::installIntoGroupBox(QGroupBox* groupBox)
-{
-    return new GroupBoxCollapser(groupBox);
-}
-
-GroupBoxCollapser* GroupBoxCollapser::installIntoGroupBox2(QGroupBox* groupBox, bool& expanded)
-{
-    auto* result = new GroupBoxCollapser(groupBox);
-    connect(result, &GroupBoxCollapser::toggled, [&expanded](bool b) { expanded = b; });
-    return result;
-}
-
-GroupBoxCollapser* GroupBoxCollapser::findInstalledCollapser(QGroupBox* groupBox)
-{
-    if (groupBox == nullptr)
-        return nullptr;
-    return groupBox->findChild<GroupBoxCollapser*>();
-}
-
-void GroupBoxCollapser::setTitle(const QString& title)
-{
-    m_toggleButton->setText(title);
-}
-
-void GroupBoxCollapser::addTitleAction(QAction* action)
-{
-    auto* btn = new QToolButton(m_titleWidget);
-    btn->setToolButtonStyle(Qt::ToolButtonIconOnly);
-    btn->setDefaultAction(action);
-    if (action->menu() != nullptr)
-        btn->setPopupMode(QToolButton::InstantPopup);
-
-    m_titleLayout->addWidget(btn);
-
-    connect(action, &QAction::changed, [=]() { btn->setVisible(action->isVisible()); });
-}
-
-void GroupBoxCollapser::addTitleWidget(QWidget* widget)
-{
-    m_titleLayout->addWidget(widget);
-}
-
-QWidget* GroupBoxCollapser::contentArea() const
-{
-    return m_contentArea;
-}
-
-GroupBoxCollapser::GroupBoxCollapser(QGroupBox* groupBox)
-    : QObject(groupBox)
-{
-    m_toggleButton = new QToolButton(groupBox);
-    m_toggleButton->setObjectName("GroupBoxToggler");
-    m_toggleButton->setToolButtonStyle(Qt::ToolButtonTextBesideIcon);
-    m_toggleButton->setCheckable(true);
-    m_toggleButton->setText(groupBox->title());
-    m_toggleButton->setArrowType(Qt::ArrowType::DownArrow);
-    m_toggleButton->setChecked(true);
-    m_toggleButton->setSizePolicy(QSizePolicy::Minimum, QSizePolicy::MinimumExpanding);
-
-    m_titleLayout = new QHBoxLayout;
-    m_titleLayout->setSpacing(3);
-    m_titleLayout->setAlignment(Qt::AlignVCenter);
-    m_titleLayout->addWidget(m_toggleButton);
-
-    m_titleWidget = new QWidget(groupBox);
-    m_titleWidget->setObjectName("GroupBoxTitleWidget");
-    m_titleWidget->setAttribute(Qt::WA_StyledBackground, true);
-    m_titleWidget->setLayout(m_titleLayout);
-
-    m_contentArea = new QWidget(groupBox);
-    m_contentArea->setObjectName("ContentArea");
-    m_contentArea->setLayout(groupBox->layout());
-
-    auto* mainLayout = new QVBoxLayout;
-    mainLayout->setSpacing(0);
-    mainLayout->setMenuBar(m_titleWidget);
-    mainLayout->addWidget(m_contentArea);
-
-    groupBox->setTitle("");          // title has been read above
-    groupBox->setLayout(mainLayout); // overwrites layout that has been read above
-
-    connect(m_toggleButton, &QAbstractButton::clicked, this, &GroupBoxCollapser::toggle,
-            Qt::UniqueConnection);
-}
-
-void GroupBoxCollapser::toggle(bool checked)
-{
-    m_toggleButton->setArrowType(checked ? Qt::ArrowType::DownArrow : Qt::ArrowType::RightArrow);
-
-    if (m_toggleButton->isChecked())
-        m_contentArea->show();
-    else
-        m_contentArea->hide();
-    emit toggled(m_toggleButton->isChecked());
-}
diff --git a/GUI/View/Widget/GroupBoxes.h b/GUI/View/Widget/GroupBoxes.h
index e44a8f4a90a24a8e0f0dadd96efaf5ca87adac40..a1e5cbef8072e615469e2f42a18a6fbefd6e1fe1 100644
--- a/GUI/View/Widget/GroupBoxes.h
+++ b/GUI/View/Widget/GroupBoxes.h
@@ -51,52 +51,4 @@ private:
     QWidget* m_body;
 };
 
-
-//! Add-on to group boxes to make them collapsible.
-//!
-//! Also adds the possibility to show toolbuttons or widgets in the group box's title.
-//! This add-on takes the layout (plus the contained widgets) of a given group box and moves it into
-//! a newly created content area widget. A title widget will be added, and the original group box
-//! title will be hidden.
-//!
-//! To support style sheets, the custom bool property "collapsible" will be added to the group box
-//! an set to true.
-class GroupBoxCollapser : public QObject {
-    Q_OBJECT
-public:
-    static GroupBoxCollapser* installIntoGroupBox(QGroupBox* groupBox);
-    static GroupBoxCollapser* installIntoGroupBox2(QGroupBox* groupBox, bool& expanded);
-    static GroupBoxCollapser* findInstalledCollapser(QGroupBox* groupBox);
-
-    //! Set the title of the group box. Do not use the method groupBox->setTitle() any more once the
-    //! add-on is installed.
-    void setTitle(const QString& title);
-
-    //! Add a tool button to the title bar, connected to the given action
-    void addTitleAction(QAction* action);
-
-    //! Add a widget to the title bar.
-    void addTitleWidget(QWidget* widget);
-
-    //! The content area, to which the found group box content has been moved when the add-on has
-    //! been installed.
-    QWidget* contentArea() const;
-
-    //! Expand/collapse the content area
-    void setExpanded(bool expanded = true);
-
-signals:
-    void toggled(bool b);
-
-private:
-    GroupBoxCollapser(QGroupBox* groupBox);
-    void toggle(bool checked);
-
-    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_contentArea;      //!< widget to where the original group box content has been moved
-};
-
-
 #endif // BORNAGAIN_GUI_VIEW_WIDGET_GROUPBOXES_H