QTitanRibbon 6.5.0 breaks viewport resize in QAbstractScrollArea

#include <QApplication>
#include <QHeaderView>
#include <QTableWidget>

#include <QtitanRibbon.h>
#include <QtnRibbonMainWindow.h>

class MainWindow : public RibbonMainWindow
{
  Q_OBJECT

 public:
  MainWindow()
      : RibbonMainWindow()
  {

    auto tableWidget = new QTableWidget( 20, 2, this );
    tableWidget->horizontalHeader()->setSectionResizeMode( QHeaderView::Stretch );

    for ( int row = 0; row < tableWidget->rowCount(); ++row )
      {
        for ( int column = 0; column < tableWidget->columnCount(); ++column )
          {
            QTableWidgetItem* newItem = new QTableWidgetItem( tr( "%1" ).arg( ( row + 1 ) * ( column + 1 ) ) );
            newItem->setTextAlignment( Qt::AlignRight );
            tableWidget->setItem( row, column, newItem );
          }
      }

    setCentralWidget( tableWidget );
    setWindowTitle( tr( "TableView Test" ) );

    // This line causes the scrollbar to overlap the viewport of the tableWidget.
    // Comment out to get tableWidget with non-overlapping scrollbar
    ribbonBar()->addPage( tr( "First Page" ) );
  }
};

int main( int argc, char* argv[] )
{
  QApplication app( argc, argv );
  MainWindow mw;
  mw.show();
  return app.exec();
}

#include "main.moc"

horizontalScrollBar()->setStyleSheet("QScrollBar {height:15px;}");
verticalScrollBar()->setStyleSheet("QScrollBar {width:15px;}");