diff --git a/Polyhedron/demo/Polyhedron/Plugins/Surface_mesh/Surface_mesh_approximation_dockwidget.ui b/Polyhedron/demo/Polyhedron/Plugins/Surface_mesh/Surface_mesh_approximation_dockwidget.ui
index 991f943d413..65b1d9a5f1e 100644
--- a/Polyhedron/demo/Polyhedron/Plugins/Surface_mesh/Surface_mesh_approximation_dockwidget.ui
+++ b/Polyhedron/demo/Polyhedron/Plugins/Surface_mesh/Surface_mesh_approximation_dockwidget.ui
@@ -6,8 +6,8 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>654</width>
-    <height>360</height>
+    <width>717</width>
+    <height>356</height>
    </rect>
   </property>
   <property name="windowTitle">
@@ -64,74 +64,27 @@
        </item>
        <item>
         <layout class="QGridLayout" name="gridLayout_2">
-         <item row="3" column="0">
-          <widget class="QLabel" name="label_2">
-           <property name="text">
-            <string>#Relaxations</string>
-           </property>
-          </widget>
-         </item>
-         <item row="3" column="2">
-          <widget class="QSpinBox" name="nb_relaxations">
-           <property name="alignment">
-            <set>Qt::AlignRight|Qt::AlignTrailing|Qt::AlignVCenter</set>
-           </property>
-           <property name="buttonSymbols">
-            <enum>QAbstractSpinBox::NoButtons</enum>
-           </property>
-           <property name="value">
-            <number>5</number>
-           </property>
-          </widget>
-         </item>
          <item row="2" column="0">
-          <widget class="QCheckBox" name="cb_error_drop">
+          <widget class="QLabel" name="label_9">
+           <property name="toolTip">
+            <string/>
+           </property>
            <property name="text">
             <string>Error drop</string>
            </property>
-           <property name="autoExclusive">
-            <bool>true</bool>
-           </property>
-          </widget>
-         </item>
-         <item row="2" column="2">
-          <widget class="QDoubleSpinBox" name="error_drop">
-           <property name="enabled">
-            <bool>false</bool>
-           </property>
-           <property name="alignment">
-            <set>Qt::AlignRight|Qt::AlignTrailing|Qt::AlignVCenter</set>
-           </property>
-           <property name="buttonSymbols">
-            <enum>QAbstractSpinBox::NoButtons</enum>
-           </property>
-           <property name="decimals">
-            <number>4</number>
-           </property>
-           <property name="minimum">
-            <double>0.000100000000000</double>
-           </property>
-           <property name="maximum">
-            <double>1.000000000000000</double>
-           </property>
-           <property name="singleStep">
-            <double>0.010000000000000</double>
-           </property>
-           <property name="value">
-            <double>0.010000000000000</double>
-           </property>
           </widget>
          </item>
          <item row="0" column="0">
-          <widget class="QCheckBox" name="cb_nb_proxies">
+          <widget class="QLabel" name="label_8">
            <property name="text">
             <string>#Proxies</string>
            </property>
-           <property name="checked">
-            <bool>true</bool>
-           </property>
-           <property name="autoExclusive">
-            <bool>true</bool>
+          </widget>
+         </item>
+         <item row="3" column="0">
+          <widget class="QLabel" name="label_2">
+           <property name="text">
+            <string>#Relaxations</string>
            </property>
           </widget>
          </item>
@@ -164,6 +117,50 @@
            </property>
           </spacer>
          </item>
+         <item row="2" column="2">
+          <widget class="QDoubleSpinBox" name="error_drop">
+           <property name="enabled">
+            <bool>true</bool>
+           </property>
+           <property name="toolTip">
+            <string>Negative value is ignored</string>
+           </property>
+           <property name="alignment">
+            <set>Qt::AlignRight|Qt::AlignTrailing|Qt::AlignVCenter</set>
+           </property>
+           <property name="buttonSymbols">
+            <enum>QAbstractSpinBox::NoButtons</enum>
+           </property>
+           <property name="decimals">
+            <number>4</number>
+           </property>
+           <property name="minimum">
+            <double>-1.000000000000000</double>
+           </property>
+           <property name="maximum">
+            <double>1.000000000000000</double>
+           </property>
+           <property name="singleStep">
+            <double>0.010000000000000</double>
+           </property>
+           <property name="value">
+            <double>-1.000000000000000</double>
+           </property>
+          </widget>
+         </item>
+         <item row="3" column="2">
+          <widget class="QSpinBox" name="nb_relaxations">
+           <property name="alignment">
+            <set>Qt::AlignRight|Qt::AlignTrailing|Qt::AlignVCenter</set>
+           </property>
+           <property name="buttonSymbols">
+            <enum>QAbstractSpinBox::NoButtons</enum>
+           </property>
+           <property name="value">
+            <number>5</number>
+           </property>
+          </widget>
+         </item>
          <item row="4" column="0">
           <widget class="QLabel" name="label">
            <property name="text">
diff --git a/Polyhedron/demo/Polyhedron/Plugins/Surface_mesh/Surface_mesh_approximation_plugin.cpp b/Polyhedron/demo/Polyhedron/Plugins/Surface_mesh/Surface_mesh_approximation_plugin.cpp
index ce5fcfef22d..b83bf4c9758 100644
--- a/Polyhedron/demo/Polyhedron/Plugins/Surface_mesh/Surface_mesh_approximation_plugin.cpp
+++ b/Polyhedron/demo/Polyhedron/Plugins/Surface_mesh/Surface_mesh_approximation_plugin.cpp
@@ -299,10 +299,8 @@ void Polyhedron_demo_surface_mesh_approximation_plugin::on_buttonSeeding_clicked
   time.start();
   approx.initialize_seeds(CGAL::parameters::seeding_method(
     static_cast<VSA::Seeding_method>(ui_widget.comboMethod->currentIndex()))
-    .max_number_of_proxies((ui_widget.cb_nb_proxies->isChecked() ?
-      boost::optional<std::size_t>(ui_widget.nb_proxies->value()) : boost::none))
-    .min_error_drop((ui_widget.cb_error_drop->isChecked() ?
-      boost::optional<EPICK::FT>(ui_widget.error_drop->value()) : boost::none))
+    .max_number_of_proxies(ui_widget.nb_proxies->value())
+    .min_error_drop(ui_widget.error_drop->value())
     .number_of_relaxations(ui_widget.nb_relaxations->value()));
   approx.run(ui_widget.nb_iterations->value());