if (index >= 0 && index == m_tabToBeClosedOnMiddleMouseButtonRelease
&& event->button() == Qt::MiddleButton) {
// Mouse middle click on a tab closes this tab.
if (index >= 0 && index == m_tabToBeClosedOnMiddleMouseButtonRelease
&& event->button() == Qt::MiddleButton) {
// Mouse middle click on a tab closes this tab.