diff --git a/Lab/demo/Lab/Plugins/Operations_on_polyhedra/Clip_polyhedron_plugin.cpp b/Lab/demo/Lab/Plugins/Operations_on_polyhedra/Clip_polyhedron_plugin.cpp
index b26e60c5d82..ffbb470c282 100644
--- a/Lab/demo/Lab/Plugins/Operations_on_polyhedra/Clip_polyhedron_plugin.cpp
+++ b/Lab/demo/Lab/Plugins/Operations_on_polyhedra/Clip_polyhedron_plugin.cpp
@@ -122,7 +122,8 @@ public :
 
     connect(ui_widget.clip_radioButton, &QRadioButton::toggled,
             [this](bool b){
-      ui_widget.close_checkBox->setEnabled(!ui_widget.do_not_modify_CheckBox->isChecked() &&b);
+      ui_widget.close_checkBox->setEnabled(!ui_widget.do_not_modify_CheckBox->isChecked() && b);
+      ui_widget.coplanarCheckBox->setEnabled(ui_widget.clip_radioButton->isChecked());
     });
     connect(actionClipPolyhedra , SIGNAL(triggered()),
             this, SLOT(pop_widget()));
@@ -235,7 +236,7 @@ public Q_SLOTS:
       for(int id : scene->selectionIndices())
       {
         Scene_surface_mesh_item *sm_item = qobject_cast<Scene_surface_mesh_item*>(scene->item(id));
-        if(sm_item && CGAL::is_triangle_mesh(*sm_item->polyhedron()))
+        if(sm_item)
         {
           if(!ui_widget.do_not_modify_CheckBox->isChecked() && CGAL::Polygon_mesh_processing::does_self_intersect(*sm_item->face_graph()))
             CGAL::Three::Three::warning(tr("%1 has not been clipped because it has self intersections.").arg(sm_item->name()));
@@ -255,10 +256,10 @@ public Q_SLOTS:
             {
               CGAL::Polygon_mesh_processing::clip(*(sm_item->face_graph()),
                                                   plane->plane(),
-                                                  CGAL::parameters::clip_volume(
-                                                    ui_widget.close_checkBox->isChecked()).
-                                                  throw_on_self_intersection(true).
-                                                  use_compact_clipper(
+                                                  CGAL::parameters::clip_volume(ui_widget.close_checkBox->isChecked())
+                                                  .do_not_triangulate_faces(!ui_widget.triangulated_checkBox->isChecked())
+                                                  .throw_on_self_intersection(true)
+                                                  .use_compact_clipper(
                                                     !ui_widget.coplanarCheckBox->isChecked())
                                                   .allow_self_intersections(ui_widget.do_not_modify_CheckBox->isChecked()));
             }
@@ -280,6 +281,7 @@ public Q_SLOTS:
                 CGAL::Polygon_mesh_processing::split(*(sm_item->face_graph()),
                                                     plane->plane(),
                                                      CGAL::parameters::throw_on_self_intersection(true)
+                                                     .do_not_triangulate_faces(!ui_widget.triangulated_checkBox->isChecked())
                                                      .allow_self_intersections(ui_widget.do_not_modify_CheckBox->isChecked()));
               }
             }
diff --git a/Lab/demo/Lab/Plugins/Operations_on_polyhedra/Clip_polyhedron_plugin.ui b/Lab/demo/Lab/Plugins/Operations_on_polyhedra/Clip_polyhedron_plugin.ui
index db5d02c4ba1..bccb4d741a8 100644
--- a/Lab/demo/Lab/Plugins/Operations_on_polyhedra/Clip_polyhedron_plugin.ui
+++ b/Lab/demo/Lab/Plugins/Operations_on_polyhedra/Clip_polyhedron_plugin.ui
@@ -6,8 +6,8 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>386</width>
-    <height>231</height>
+    <width>326</width>
+    <height>358</height>
    </rect>
   </property>
   <property name="sizePolicy">
@@ -56,33 +56,86 @@
      </layout>
     </item>
     <item>
-     <layout class="QVBoxLayout" name="verticalLayout">
-      <item>
-       <widget class="QGroupBox" name="groupBox">
-        <property name="sizePolicy">
-         <sizepolicy hsizetype="Preferred" vsizetype="Expanding">
-          <horstretch>0</horstretch>
-          <verstretch>0</verstretch>
-         </sizepolicy>
-        </property>
-        <property name="title">
-         <string>Behavior</string>
-        </property>
-        <layout class="QGridLayout" name="gridLayout" rowstretch="0,0,0,0,0,0,0" columnstretch="1,0">
-         <item row="6" column="1">
-          <spacer name="verticalSpacer">
-           <property name="orientation">
-            <enum>Qt::Vertical</enum>
+     <layout class="QVBoxLayout" name="verticalLayout"/>
+    </item>
+    <item>
+     <spacer name="verticalSpacer_2">
+      <property name="orientation">
+       <enum>Qt::Vertical</enum>
+      </property>
+      <property name="sizeHint" stdset="0">
+       <size>
+        <width>20</width>
+        <height>40</height>
+       </size>
+      </property>
+     </spacer>
+    </item>
+    <item>
+     <widget class="QGroupBox" name="groupBox">
+      <property name="sizePolicy">
+       <sizepolicy hsizetype="Preferred" vsizetype="Expanding">
+        <horstretch>0</horstretch>
+        <verstretch>0</verstretch>
+       </sizepolicy>
+      </property>
+      <property name="title">
+       <string>Behavior</string>
+      </property>
+      <layout class="QVBoxLayout" name="verticalLayout_5">
+       <item>
+        <layout class="QHBoxLayout" name="horizontalLayout_2">
+         <item>
+          <widget class="QRadioButton" name="clip_radioButton">
+           <property name="text">
+            <string>Clip</string>
            </property>
-           <property name="sizeHint" stdset="0">
-            <size>
-             <width>20</width>
-             <height>40</height>
-            </size>
+           <property name="checked">
+            <bool>true</bool>
            </property>
-          </spacer>
+          </widget>
          </item>
-         <item row="4" column="0">
+         <item>
+          <widget class="QRadioButton" name="split_radioButton">
+           <property name="text">
+            <string>Split</string>
+           </property>
+          </widget>
+         </item>
+        </layout>
+       </item>
+       <item>
+        <layout class="QVBoxLayout" name="verticalLayout_3">
+         <item>
+          <widget class="QCheckBox" name="close_checkBox">
+           <property name="layoutDirection">
+            <enum>Qt::LeftToRight</enum>
+           </property>
+           <property name="autoFillBackground">
+            <bool>false</bool>
+           </property>
+           <property name="text">
+            <string>&amp;Keep Closed</string>
+           </property>
+          </widget>
+         </item>
+         <item>
+          <widget class="QCheckBox" name="triangulated_checkBox">
+           <property name="layoutDirection">
+            <enum>Qt::LeftToRight</enum>
+           </property>
+           <property name="autoFillBackground">
+            <bool>false</bool>
+           </property>
+           <property name="text">
+            <string>&amp;Keep Triangulated</string>
+           </property>
+           <property name="checked">
+            <bool>true</bool>
+           </property>
+          </widget>
+         </item>
+         <item>
           <widget class="QCheckBox" name="coplanarCheckBox">
            <property name="enabled">
             <bool>true</bool>
@@ -99,37 +152,7 @@ Only available in Split mode.</string>
            </property>
           </widget>
          </item>
-         <item row="1" column="0">
-          <widget class="QCheckBox" name="close_checkBox">
-           <property name="layoutDirection">
-            <enum>Qt::LeftToRight</enum>
-           </property>
-           <property name="autoFillBackground">
-            <bool>false</bool>
-           </property>
-           <property name="text">
-            <string>&amp;Keep Closed</string>
-           </property>
-          </widget>
-         </item>
-         <item row="0" column="1">
-          <widget class="QRadioButton" name="split_radioButton">
-           <property name="text">
-            <string>Split</string>
-           </property>
-          </widget>
-         </item>
-         <item row="0" column="0">
-          <widget class="QRadioButton" name="clip_radioButton">
-           <property name="text">
-            <string>Clip</string>
-           </property>
-           <property name="checked">
-            <bool>true</bool>
-           </property>
-          </widget>
-         </item>
-         <item row="5" column="0">
+         <item>
           <widget class="QCheckBox" name="do_not_modify_CheckBox">
            <property name="toolTip">
             <string>Allow the use of a self-intersected clipper, but prevent the closing of the result.</string>
@@ -139,20 +162,11 @@ Only available in Split mode.</string>
            </property>
           </widget>
          </item>
-         <item row="5" column="1">
-          <widget class="QPushButton" name="flip_Button">
-           <property name="sizePolicy">
-            <sizepolicy hsizetype="Minimum" vsizetype="Preferred">
-             <horstretch>0</horstretch>
-             <verstretch>0</verstretch>
-            </sizepolicy>
-           </property>
-           <property name="text">
-            <string>Flip plane</string>
-           </property>
-          </widget>
-         </item>
-         <item row="4" column="1">
+        </layout>
+       </item>
+       <item>
+        <layout class="QVBoxLayout" name="verticalLayout_4">
+         <item>
           <widget class="QPushButton" name="clipButton">
            <property name="sizePolicy">
             <sizepolicy hsizetype="Minimum" vsizetype="Preferred">
@@ -165,23 +179,36 @@ Only available in Split mode.</string>
            </property>
           </widget>
          </item>
+         <item>
+          <widget class="QPushButton" name="flip_Button">
+           <property name="sizePolicy">
+            <sizepolicy hsizetype="Minimum" vsizetype="Preferred">
+             <horstretch>0</horstretch>
+             <verstretch>0</verstretch>
+            </sizepolicy>
+           </property>
+           <property name="text">
+            <string>Flip plane</string>
+           </property>
+          </widget>
+         </item>
         </layout>
-       </widget>
-      </item>
-     </layout>
-    </item>
-    <item>
-     <spacer name="verticalSpacer_2">
-      <property name="orientation">
-       <enum>Qt::Vertical</enum>
-      </property>
-      <property name="sizeHint" stdset="0">
-       <size>
-        <width>20</width>
-        <height>40</height>
-       </size>
-      </property>
-     </spacer>
+       </item>
+       <item>
+        <spacer name="verticalSpacer">
+         <property name="orientation">
+          <enum>Qt::Vertical</enum>
+         </property>
+         <property name="sizeHint" stdset="0">
+          <size>
+           <width>20</width>
+           <height>40</height>
+          </size>
+         </property>
+        </spacer>
+       </item>
+      </layout>
+     </widget>
     </item>
    </layout>
   </widget>