GUI: Fix shift-click selection on macOS

Implement custom mouse press event handling for macOS to properly support shift-click range selection in the transfer list. This addresses the issue reported in QTBUG-115838.

src/gui/transferlistwidget.cpp

@@ -1446,3 +1446,38 @@ void TransferListWidget::wheelEvent(QWheelEvent *event)
 
     QTreeView::wheelEvent(event);  // event delegated to base class
 }
+
+#ifdef Q_OS_MACOS
+void TransferListWidget::mousePressEvent(QMouseEvent *event)
+{
+    const QModelIndex clickedIndex = indexAt(event->pos());
+    if (!clickedIndex.isValid())
+    {
+        QTreeView::mousePressEvent(event);
+        return;
+    }
+
+    const Qt::KeyboardModifiers modifiers = event->modifiers();
+    const bool shiftPressed = modifiers.testFlag(Qt::ShiftModifier);
+    const bool cmdPressed = modifiers.testFlag(Qt::ControlModifier);  // Command key on macOS
+
+    if (shiftPressed && m_lastClickedIndex.isValid())
+    {
+        // Handle shift-click range selection
+        const QItemSelection selection(m_lastClickedIndex, clickedIndex);
+        if (cmdPressed)
+            selectionModel()->select(selection, QItemSelectionModel::Select | QItemSelectionModel::Rows);
+        else
+            selectionModel()->select(selection, QItemSelectionModel::ClearAndSelect | QItemSelectionModel::Rows);
+        selectionModel()->setCurrentIndex(clickedIndex, QItemSelectionModel::NoUpdate);
+        event->accept();
+        return;
+    }
+
+    // For non-shift clicks, update the last clicked index
+    if (!(modifiers & (Qt::AltModifier | Qt::MetaModifier)))  // Ignore if Alt/Meta is pressed
+        m_lastClickedIndex = clickedIndex;
+
+    QTreeView::mousePressEvent(event);
+}
+#endif

src/gui/transferlistwidget.h

@@ -118,11 +118,14 @@ private slots:
     void askNewCategoryForSelection();
     void saveSettings();
 
-private:
+protected:
     void dragEnterEvent(QDragEnterEvent *event) override;
     void dragMoveEvent(QDragMoveEvent *event) override;
     void dropEvent(QDropEvent *event) override;
     void wheelEvent(QWheelEvent *event) override;
+    void mousePressEvent(QMouseEvent *event) override;
+
+private:
     QModelIndex mapToSource(const QModelIndex &index) const;
     QModelIndexList mapToSource(const QModelIndexList &indexes) const;
     QModelIndex mapFromSource(const QModelIndex &index) const;
@@ -139,4 +142,7 @@ private:
 
     TransferListModel *m_listModel = nullptr;
     TransferListSortModel *m_sortFilterModel = nullptr;
+#ifdef Q_OS_MACOS
+    QPersistentModelIndex m_lastClickedIndex;  // For handling shift-click selection on macOS
+#endif
 };