diff --git a/GUI/Model/Sample/CoreAndShellItem.h b/GUI/Model/Sample/CoreAndShellItem.h
index eaa949b6c0a3730c083d9db6708ce95835f7e0db..a6368de15ab13b526daf399150e07ba9df45bc66 100644
--- a/GUI/Model/Sample/CoreAndShellItem.h
+++ b/GUI/Model/Sample/CoreAndShellItem.h
@@ -42,14 +42,6 @@ public:
     bool expandMain = true;
     bool expandCore = true;
     bool expandShell = true;
-    bool isExpandMain() const { return expandMain; }
-    void setExpandMain(bool b) { expandMain = b; }
-
-    bool isExpandCore() const { return expandCore; }
-    void setExpandCore(bool b) { expandCore = b; }
-
-    bool isExpandShell() const { return expandShell; }
-    void setExpandShell(bool b) { expandShell = b; }
 
 private:
     std::unique_ptr<ParticleItem> m_core;
diff --git a/GUI/View/SampleDesigner/CoreAndShellForm.cpp b/GUI/View/SampleDesigner/CoreAndShellForm.cpp
index e44f7108fcfcd4592311674dbdfc86e7209d13e0..ef171b82d6c443bfb8fba4ec040472e909423cd3 100644
--- a/GUI/View/SampleDesigner/CoreAndShellForm.cpp
+++ b/GUI/View/SampleDesigner/CoreAndShellForm.cpp
@@ -76,16 +76,14 @@ CoreAndShellForm::CoreAndShellForm(QWidget* parent, CoreAndShellItem* coreShellI
         connect(core.formfactorCombo, QOverload<int>::of(&QComboBox::currentIndexChanged), this,
                 &CoreAndShellForm::onCoreComboChanged);
         core.layouter->addRow("Form factor:", core.formfactorCombo);
-        core.collapser = GroupBoxCollapser::installIntoGroupBox(coreParticleGroup);
+        core.collapser = GroupBoxCollapser::installIntoGroupBox(coreParticleGroup,
+	    coreShellItem->expandCore);
 
         auto* showInRealspaceAction =
             ActionFactory::createShowInRealspaceAction(this, "core particle");
         connect(showInRealspaceAction, &QAction::triggered, this,
                 &CoreAndShellForm::showCoreInRealspace);
         core.collapser->addTitleAction(showInRealspaceAction);
-        core.collapser->setExpanded(coreShellItem->isExpandCore());
-        connect(core.collapser, &GroupBoxCollapser::toggled, this,
-                [coreShellItem](bool b) { coreShellItem->setExpandCore(b); });
 
         createCoreWidgets();
 
@@ -104,10 +102,7 @@ CoreAndShellForm::CoreAndShellForm(QWidget* parent, CoreAndShellItem* coreShellI
         connect(shell.formfactorCombo, QOverload<int>::of(&QComboBox::currentIndexChanged), this,
                 &CoreAndShellForm::onShellComboChanged);
         shell.layouter->addRow("Form factor:", shell.formfactorCombo);
-        shell.collapser = GroupBoxCollapser::installIntoGroupBox(shellParticleGroup);
-        shell.collapser->setExpanded(coreShellItem->isExpandShell());
-        connect(shell.collapser, &GroupBoxCollapser::toggled, this,
-                [coreShellItem](bool b) { coreShellItem->setExpandShell(b); });
+        GroupBoxCollapser::installIntoGroupBox(shellParticleGroup, coreShellItem->expandShell);
 
         auto* showInRealspaceAction =
             ActionFactory::createShowInRealspaceAction(this, "shell particle");
@@ -120,10 +115,7 @@ CoreAndShellForm::CoreAndShellForm(QWidget* parent, CoreAndShellItem* coreShellI
         layouter.addRow(shellParticleGroup);
     }
 
-    auto* mainCollapser = GroupBoxCollapser::installIntoGroupBox(this);
-    mainCollapser->setExpanded(coreShellItem->isExpandMain());
-    connect(mainCollapser, &GroupBoxCollapser::toggled, this,
-            [coreShellItem](bool b) { coreShellItem->setExpandMain(b); });
+    auto* mainCollapser = GroupBoxCollapser::installIntoGroupBox(this, coreShellItem->expandMain);
 
     // top right corner actions
     // show in real space