Fix #26507: Crash when revealing instruments in a custom part

src/instrumentsscene/qml/MuseScore/InstrumentsScene/LayoutPanel.qml

@@ -319,8 +319,12 @@ Item {
                                     flickable.contentY = contentYBackup
                                 }
 
-                                onVisibilityChanged: function(visible) {
-                                    treeModel.toggleVisibilityOfSelectedRows(visible);
+                                onChangeVisibilityOfSelectedRowsRequested: function(visible) {
+                                    treeModel.changeVisibilityOfSelectedRows(visible);
+                                }
+
+                                onChangeVisibilityRequested: function(index, visible) {
+                                    treeModel.changeVisibility(index, visible)
                                 }
 
                                 onDragStarted: {

src/instrumentsscene/qml/MuseScore/InstrumentsScene/internal/LayoutPanelItemDelegate.qml

@@ -54,7 +54,8 @@ FocusableControl {
     signal popupOpened(var popupX, var popupY, var popupHeight)
     signal popupClosed()
 
-    signal visibilityChanged(bool visible)
+    signal changeVisibilityOfSelectedRowsRequested(bool visible)
+    signal changeVisibilityRequested(var index, bool visible)
 
     signal dragStarted()
     signal dropped()
@@ -231,9 +232,9 @@ FocusableControl {
                 }
 
                 if (root.isSelected) {
-                    root.visibilityChanged(!isVisible)
+                    root.changeVisibilityOfSelectedRowsRequested(!isVisible)
                 } else {
-                    model.itemRole.isVisible = !isVisible
+                    root.changeVisibilityRequested(styleData.index, !isVisible)
                 }
             }
         }

src/instrumentsscene/view/abstractlayoutpaneltreeitem.h

@@ -51,7 +51,7 @@ class AbstractLayoutPanelTreeItem : public QObject
     Q_PROPERTY(QString id READ idStr CONSTANT)
     Q_PROPERTY(QString title READ title WRITE setTitle NOTIFY titleChanged)
     Q_PROPERTY(int type READ typeInt CONSTANT)
-    Q_PROPERTY(bool isVisible READ isVisible WRITE setIsVisible NOTIFY isVisibleChanged)
+    Q_PROPERTY(bool isVisible READ isVisible NOTIFY isVisibleChanged)
     Q_PROPERTY(bool isExpandable READ isExpandable NOTIFY isExpandableChanged)
     Q_PROPERTY(bool isRemovable READ isRemovable NOTIFY isRemovableChanged)
     Q_PROPERTY(bool isSelectable READ isSelectable CONSTANT)

src/instrumentsscene/view/layoutpaneltreemodel.cpp

@@ -33,7 +33,6 @@
 
 #include "uicomponents/view/itemmultiselectionmodel.h"
 
-#include "async/async.h"
 #include "defer.h"
 #include "log.h"
 
@@ -152,6 +151,8 @@ bool LayoutPanelTreeModel::removeRows(int row, int count, const QModelIndex& par
 
     emit isEmptyChanged();
 
+    updateSystemObjectLayers();
+
     return true;
 }
 
@@ -223,10 +224,10 @@ void LayoutPanelTreeModel::setupPartsConnections()
     });
 
     m_notation->parts()->systemObjectStavesChanged().onNotify(this, [this]() {
-        // Wait until parts are fully loaded / updated
-        async::Async::call(this, [this]() {
+        m_shouldUpdateSystemObjectLayers = true;
+        if (!m_isLoadingBlocked) {
             updateSystemObjectLayers();
-        });
+        }
     });
 }
 
@@ -521,6 +522,7 @@ bool LayoutPanelTreeModel::moveRows(const QModelIndex& sourceParent, int sourceR
     endMoveRows();
 
     updateRearrangementAvailability();
+    updateSystemObjectLayers();
 
     return true;
 }
@@ -543,17 +545,27 @@ void LayoutPanelTreeModel::endActiveDrag()
     m_dragInProgress = false;
 
     setLoadingBlocked(false);
+
+    updateSystemObjectLayers();
 }
 
-void LayoutPanelTreeModel::toggleVisibilityOfSelectedRows(bool visible)
+void LayoutPanelTreeModel::changeVisibilityOfSelectedRows(bool visible)
 {
     for (const QModelIndex& index : m_selectionModel->selectedIndexes()) {
-        AbstractLayoutPanelTreeItem* item = modelIndexToItem(index);
-
-        item->setIsVisible(visible);
+        changeVisibility(index, visible);
     }
 }
 
+void LayoutPanelTreeModel::changeVisibility(const QModelIndex& index, bool visible)
+{
+    setLoadingBlocked(true);
+
+    AbstractLayoutPanelTreeItem* item = modelIndexToItem(index);
+    item->setIsVisible(visible);
+
+    setLoadingBlocked(false);
+}
+
 QItemSelectionModel* LayoutPanelTreeModel::selectionModel() const
 {
     return m_selectionModel;
@@ -928,10 +940,12 @@ void LayoutPanelTreeModel::updateSystemObjectLayers()
 {
     TRACEFUNC;
 
-    if (!m_masterNotation || !m_rootItem) {
+    if (!m_masterNotation || !m_rootItem || !m_shouldUpdateSystemObjectLayers) {
         return;
     }
 
+    m_shouldUpdateSystemObjectLayers = false;
+
     // Create copy, because we're going to modify them
     std::vector<Staff*> newSystemObjectStaves = m_masterNotation->notation()->parts()->systemObjectStaves();
     QList<AbstractLayoutPanelTreeItem*> children = m_rootItem->childItems();

src/instrumentsscene/view/layoutpaneltreemodel.h

@@ -92,7 +92,8 @@ class LayoutPanelTreeModel : public QAbstractItemModel, public muse::async::Asyn
     Q_INVOKABLE void moveSelectedRowsUp();
     Q_INVOKABLE void moveSelectedRowsDown();
     Q_INVOKABLE void removeSelectedRows();
-    Q_INVOKABLE void toggleVisibilityOfSelectedRows(bool visible);
+    Q_INVOKABLE void changeVisibilityOfSelectedRows(bool visible);
+    Q_INVOKABLE void changeVisibility(const QModelIndex& index, bool visible);
 
     Q_INVOKABLE void startActiveDrag();
     Q_INVOKABLE void endActiveDrag();
@@ -181,6 +182,8 @@ private slots:
 
     bool m_layoutPanelVisible = true;
 
+    bool m_shouldUpdateSystemObjectLayers = false;
+
     bool m_dragInProgress = false;
     AbstractLayoutPanelTreeItem* m_dragSourceParentItem = nullptr;
     MoveParams m_activeDragMoveParams;