[m.i810c] Fix expanded/collapsed state of layer in sample editor(#810) (Closes #810)

Merging branch 'm.i810c'  into 'main'.

See merge request !2087

GUI/View/SampleDesigner/SampleEditorController.cpp

@@ -67,7 +67,7 @@ void SampleEditorController::addLayerItem(LayerItem* before)
     LayerItem* layer = m_sampleItem->createLayerItemAt(i);
     layer->setMaterial(materialModel()->defaultMaterialItem());
     layer->setColor(color);
-
+    layer->expandLayer = true; // manually added layer => expanded
     onLayerAdded(layer);
 }
 

GUI/View/Widget/GroupBoxes.cpp

@@ -72,7 +72,7 @@ CollapsibleGroupBox::CollapsibleGroupBox(const QString& title, QWidget* parent,
     m_toggleButton->setCheckable(true);
     m_toggleButton->setText(title);
     m_toggleButton->setArrowType(Qt::ArrowType::DownArrow);
-    m_toggleButton->setChecked(true);
+    m_toggleButton->setChecked(expanded);
     m_toggleButton->setSizePolicy(QSizePolicy::Minimum, QSizePolicy::MinimumExpanding);
 
     //... Body
@@ -81,6 +81,7 @@ CollapsibleGroupBox::CollapsibleGroupBox(const QString& title, QWidget* parent,
     layout->addWidget(m_body);
     m_body->setObjectName("ContentArea"); // stylesheet -> transparent background
     m_body->setVisible(expanded);
+    m_toggleButton->setArrowType(expanded ? Qt::ArrowType::DownArrow : Qt::ArrowType::RightArrow);
 
     connect(m_toggleButton, &QAbstractButton::clicked,
             [tb = m_toggleButton, bo = m_body, &expanded](bool checked) {