QTabWidget display is messed up by adding setCornerWidget in a dark background.

// code placeholder

QTabWidget *tabWidget = new QTabWidget();
tabWidget->setStyleSheet("QTabBar {background: #2e2f30;}"
			 "QToolButton {background: #2e2f30; border: 0px solid #2e2f30;}");

QAction *actionNew_Tab = new QAction();
actionNew_Tab->setIcon(QIcon(":/resources/images/newTab.svg"));

QToolButton *newTabButton = new QToolButton();
newTabButton->setDefaultAction(actionNew_Tab);

tabWidget->setCornerWidget(newTabButton, Qt::TopRightCorner);