I am using QTabWidget in my project. Is there any stron reason I should use QTabBar and not QTabWidget?
What advantages I have if I use QTabWidget?
QTabWidget associates a QWidget to each tab of a QTabBar. So widget management when switching from one tab to an other is already done by the QTabWidget class. It was done for convenience. See documentation for more details : http://doc.qt.io/qt-4.8/qtabwidget.html#details.
QTabBar is only a tab bar. You can do every thing you want when switching from one tab to an other. More details.
The best advantage is that QTabWidget combines QTabBar AND QStackedWidget behaviors.