diff --git a/src/Gui/CMakeLists.txt b/src/Gui/CMakeLists.txt
index 89b0a5e297..6ad901f9dd 100644
--- a/src/Gui/CMakeLists.txt
+++ b/src/Gui/CMakeLists.txt
@@ -4,7 +4,7 @@ add_subdirectory(PreferencePacks)
 add_subdirectory(PreferencePackTemplates)
 
 if(WIN32)
-add_definitions(-DFCGui -DQIIS_MAKEDLL -DQSINT_MAKEDLL -DOVR_OS_WIN32 -DQUARTER_INTERNAL -DQUARTER_MAKE_DLL -DCOIN_DLL)
+add_definitions(-DFCGui -DQSINT_MAKEDLL -DOVR_OS_WIN32 -DQUARTER_INTERNAL -DQUARTER_MAKE_DLL -DCOIN_DLL)
 endif(WIN32)
 
 IF(CMAKE_BUILD_TYPE)
@@ -1181,7 +1181,6 @@ SET(FreeCADGui_SRCS
     ${FreeCADGui_SDK_SRCS}
     ${FreeCADGui_CPP_SRCS}
     ${FreeCADGui_XML_SRCS}
-    ${iis_MOC_SRCS}
     ${qsint_MOC_SRCS}
     ${Gui_QRC_SRCS}
     ${Gui_UIC_HDRS}
@@ -1196,7 +1195,6 @@ SET(FreeCADGui_SRCS
     ${Language_SRCS}
     ${Propertyeditor_SRCS}
     ${Task_View_SRCS}
-    ${iisTaskPanel_SRCS}
     ${qsintActionPanel_SRCS}
     ${Resource_SRCS}
     ${Quarter_SRCS}
diff --git a/src/Gui/TaskView/TaskView.cpp b/src/Gui/TaskView/TaskView.cpp
index c6cea3eca4..71dee6e116 100644
--- a/src/Gui/TaskView/TaskView.cpp
+++ b/src/Gui/TaskView/TaskView.cpp
@@ -42,11 +42,9 @@
 #include "TaskDialog.h"
 #include "TaskEditControl.h"
 
-#if defined (QSINT_ACTIONPANEL)
 #include <Gui/QSint/actionpanel/taskgroup_p.h>
 #include <Gui/QSint/actionpanel/taskheader_p.h>
 #include <Gui/QSint/actionpanel/freecadscheme.h>
-#endif
 
 
 using namespace Gui::TaskView;
@@ -73,69 +71,6 @@ TaskWidget::~TaskWidget()
 // TaskGroup
 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 
-#if !defined (QSINT_ACTIONPANEL)
-TaskGroup::TaskGroup(QWidget *parent)
-    : iisTaskGroup(parent, false)
-{
-    setScheme(iisFreeCADTaskPanelScheme::defaultScheme());
-}
-
-TaskGroup::~TaskGroup()
-{
-}
-
-namespace Gui { namespace TaskView {
-class TaskIconLabel : public iisIconLabel {
-public:
-    TaskIconLabel(const QIcon &icon, 
-                  const QString &title,
-                  QWidget *parent = 0)
-      : iisIconLabel(icon, title, parent) {
-          // do not allow to get the focus because when hiding the task box
-          // it could cause to activate another MDI view.
-          setFocusPolicy(Qt::NoFocus);
-    }
-    void setTitle(const QString &text) {
-        myText = text;
-        update();
-    }
-};
-}
-}
-
-void TaskGroup::actionEvent (QActionEvent* e)
-{
-    QAction *action = e->action();
-    switch (e->type()) {
-    case QEvent::ActionAdded:
-        {
-            TaskIconLabel *label = new TaskIconLabel(
-                action->icon(), action->text(), this);
-            this->addIconLabel(label);
-            connect(label,SIGNAL(clicked()),action,SIGNAL(triggered()),Qt::QueuedConnection);
-            break;
-        }
-    case QEvent::ActionChanged:
-        {
-            // update label when action changes
-            QBoxLayout* bl = this->groupLayout();
-            int index = this->actions().indexOf(action);
-            if (index < 0) break;
-            QWidgetItem* item = static_cast<QWidgetItem*>(bl->itemAt(index));
-            TaskIconLabel* label = static_cast<TaskIconLabel*>(item->widget());
-            label->setTitle(action->text());
-            break;
-        }
-    case QEvent::ActionRemoved:
-        {
-            // cannot change anything
-            break;
-        }
-    default:
-        break;
-    }
-}
-#else
 TaskGroup::TaskGroup(QWidget *parent)
     : QSint::ActionBox(parent)
 {
@@ -177,19 +112,12 @@ void TaskGroup::actionEvent (QActionEvent* e)
         break;
     }
 }
-#endif
+
 //**************************************************************************
 //**************************************************************************
 // TaskBox
 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 
-#if !defined (QSINT_ACTIONPANEL)
-TaskBox::TaskBox(const QPixmap &icon, const QString &title, bool expandable, QWidget *parent)
-    : iisTaskBox(icon, title, expandable, parent), wasShown(false)
-{
-    setScheme(iisFreeCADTaskPanelScheme::defaultScheme());
-}
-#else
 TaskBox::TaskBox(QWidget *parent)
   : QSint::ActionGroup(parent), wasShown(false)
 {
@@ -228,7 +156,6 @@ QSize TaskBox::minimumSizeHint() const
     QSize s2 = QWidget::minimumSizeHint();
     return QSize(qMax(s1.width(), s2.width()), qMax(s1.height(), s2.height()));
 }
-#endif
 
 TaskBox::~TaskBox()
 {
@@ -292,28 +219,12 @@ void TaskBox::actionEvent (QActionEvent* e)
     switch (e->type()) {
     case QEvent::ActionAdded:
         {
-#if !defined (QSINT_ACTIONPANEL)
-            TaskIconLabel *label = new TaskIconLabel(
-                action->icon(), action->text(), this);
-            this->addIconLabel(label);
-            connect(label,SIGNAL(clicked()),action,SIGNAL(triggered()));
-#else
             QSint::ActionLabel *label = new QSint::ActionLabel(action, this);
             this->addActionLabel(label, true, false);
-#endif
             break;
         }
     case QEvent::ActionChanged:
         {
-#if !defined (QSINT_ACTIONPANEL)
-            // update label when action changes
-            QBoxLayout* bl = myGroup->groupLayout();
-            int index = this->actions().indexOf(action);
-            if (index < 0) break;
-            QWidgetItem* item = static_cast<QWidgetItem*>(bl->itemAt(index));
-            TaskIconLabel* label = static_cast<TaskIconLabel*>(item->widget());
-            label->setTitle(action->text());
-#endif
             break;
         }
     case QEvent::ActionRemoved:
@@ -331,7 +242,6 @@ void TaskBox::actionEvent (QActionEvent* e)
 // TaskPanel
 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 
-#if defined (QSINT_ACTIONPANEL)
 TaskPanel::TaskPanel(QWidget *parent)
   : QSint::ActionPanel(parent)
 {
@@ -355,7 +265,7 @@ QSize TaskPanel::minimumSizeHint() const
     QSize s2 = QWidget::minimumSizeHint();
     return QSize(qMax(s1.width(), s2.width()), qMax(s1.height(), s2.height()));
 }
-#endif
+
 
 //**************************************************************************
 //**************************************************************************
@@ -368,10 +278,6 @@ TaskView::TaskView(QWidget *parent)
     //addWidget(new TaskEditControl(this));
     //addWidget(new TaskAppearance(this));
     //addStretch();
-#if !defined (QSINT_ACTIONPANEL)
-    taskPanel = new iisTaskPanel(this);
-    taskPanel->setScheme(iisFreeCADTaskPanelScheme::defaultScheme());
-#else
     taskPanel = new TaskPanel(this);
     QSizePolicy sizePolicy(QSizePolicy::Preferred, QSizePolicy::Preferred);
     sizePolicy.setHorizontalStretch(0);
@@ -379,7 +285,7 @@ TaskView::TaskView(QWidget *parent)
     sizePolicy.setHeightForWidth(taskPanel->sizePolicy().hasHeightForWidth());
     taskPanel->setSizePolicy(sizePolicy);
     taskPanel->setScheme(QSint::FreeCADPanelScheme::defaultScheme());
-#endif
+
     this->setWidget(taskPanel);
     setWidgetResizable(true);
     setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
@@ -604,9 +510,7 @@ void TaskView::showDialog(TaskDialog *dlg)
         taskPanel->addWidget(ActiveCtrl);
     }
 
-#if defined (QSINT_ACTIONPANEL)
     taskPanel->setScheme(QSint::FreeCADPanelScheme::defaultScheme());
-#endif
 
     if (!dlg->needsFullSpace())
         taskPanel->addStretch();
@@ -726,7 +630,6 @@ void TaskView::addTaskWatcher(void)
         taskPanel->addStretch();
     updateWatcher();
 
-#if defined (QSINT_ACTIONPANEL)
 #if QT_VERSION >= QT_VERSION_CHECK(5, 12, 0)
     // Workaround to avoid a crash in Qt. See also
     // https://forum.freecadweb.org/viewtopic.php?f=8&t=39187
@@ -741,7 +644,6 @@ void TaskView::addTaskWatcher(void)
 #endif
 
     taskPanel->setScheme(QSint::FreeCADPanelScheme::defaultScheme());
-#endif
 }
 
 void TaskView::removeTaskWatcher(void)
@@ -819,18 +721,14 @@ void TaskView::clicked (QAbstractButton * button)
 
 void TaskView::clearActionStyle()
 {
-#if defined (QSINT_ACTIONPANEL)
     static_cast<QSint::FreeCADPanelScheme*>(QSint::FreeCADPanelScheme::defaultScheme())->clearActionStyle();
     taskPanel->setScheme(QSint::FreeCADPanelScheme::defaultScheme());
-#endif
 }
 
 void TaskView::restoreActionStyle()
 {
-#if defined (QSINT_ACTIONPANEL)
     static_cast<QSint::FreeCADPanelScheme*>(QSint::FreeCADPanelScheme::defaultScheme())->restoreActionStyle();
     taskPanel->setScheme(QSint::FreeCADPanelScheme::defaultScheme());
-#endif
 }
 
 
diff --git a/src/Gui/TaskView/TaskView.h b/src/Gui/TaskView/TaskView.h
index 77d3b6058f..e894c1b2dc 100644
--- a/src/Gui/TaskView/TaskView.h
+++ b/src/Gui/TaskView/TaskView.h
@@ -24,16 +24,10 @@
 #ifndef GUI_TASKVIEW_TASKVIEW_H
 #define GUI_TASKVIEW_TASKVIEW_H
 
-#define QSINT_ACTIONPANEL
-
 #include <vector>
 #include <QScrollArea>
 
-#if !defined (QSINT_ACTIONPANEL)
-#include <Gui/iisTaskPanel/include/iisTaskPanel>
-#else
 #include <Gui/QSint/include/QSint>
-#endif
 #include <Gui/Selection.h>
 #include "TaskWatcher.h"
 
@@ -62,19 +56,6 @@ public:
     //~TaskContent();
 };
 
-#if !defined (QSINT_ACTIONPANEL)
-class GuiExport TaskGroup : public iisTaskGroup, public TaskContent
-{
-    Q_OBJECT
-
-public:
-    TaskGroup(QWidget *parent = 0);
-    ~TaskGroup();
-
-protected:
-    void actionEvent (QActionEvent*);
-};
-#else
 class GuiExport TaskGroup : public QSint::ActionBox, public TaskContent
 {
     Q_OBJECT
@@ -88,21 +69,13 @@ public:
 protected:
     void actionEvent (QActionEvent*);
 };
-#endif
 
 /// Father class of content with header and Icon
-#if !defined (QSINT_ACTIONPANEL)
-class GuiExport TaskBox : public iisTaskBox, public TaskContent
-#else
 class GuiExport TaskBox : public QSint::ActionGroup, public TaskContent
-#endif
 {
     Q_OBJECT
 
 public:
-#if !defined (QSINT_ACTIONPANEL)
-    TaskBox(const QPixmap &icon, const QString &title, bool expandable, QWidget *parent);
-#else
     /** Constructor. Creates TaskBox without header.
       */
     explicit TaskBox(QWidget *parent = 0);
@@ -126,7 +99,7 @@ public:
                      bool expandable = true,
                      QWidget *parent = 0);
     virtual QSize minimumSizeHint() const;
-#endif
+
     ~TaskBox();
     void hideGroupBox();
     bool isGroupVisible() const;
@@ -139,7 +112,6 @@ private:
     bool wasShown;
 };
 
-#if defined (QSINT_ACTIONPANEL)
 class GuiExport TaskPanel : public QSint::ActionPanel
 {
     Q_OBJECT
@@ -149,7 +121,6 @@ public:
     virtual ~TaskPanel();
     virtual QSize minimumSizeHint() const;
 };
-#endif
 
 /// Father class of content of a Free widget (without header and Icon), shut be an exception!
 class GuiExport TaskWidget : public QWidget, public TaskContent
@@ -213,11 +184,7 @@ protected:
 
     std::vector<TaskWatcher*> ActiveWatcher;
 
-#if !defined (QSINT_ACTIONPANEL)
-    iisTaskPanel* taskPanel;
-#else
     QSint::ActionPanel* taskPanel;
-#endif
     TaskDialog *ActiveDialog;
     TaskEditControl *ActiveCtrl;
 
diff --git a/src/Mod/Mesh/Gui/DlgSmoothing.cpp b/src/Mod/Mesh/Gui/DlgSmoothing.cpp
index d491c29cae..1f2fbecdf2 100644
--- a/src/Mod/Mesh/Gui/DlgSmoothing.cpp
+++ b/src/Mod/Mesh/Gui/DlgSmoothing.cpp
@@ -150,11 +150,7 @@ TaskSmoothing::TaskSmoothing()
     selection = new Selection();
     selection->setObjects(Gui::Selection().getSelectionEx(nullptr, Mesh::Feature::getClassTypeId()));
     Gui::Selection().clearSelection();
-#if !defined (QSINT_ACTIONPANEL)
-    Gui::TaskView::TaskGroup* tasksel = new Gui::TaskView::TaskGroup();
-#else
     Gui::TaskView::TaskBox* tasksel = new Gui::TaskView::TaskBox();
-#endif
     tasksel->groupLayout()->addWidget(selection);
     tasksel->hide();
     Content.push_back(tasksel);