Impossible to change QAction text in QToolBar

How to reproduce:

1) create a QAction object, then add it to QToolBar of an example app (QMainWindow)

2) try to change text dynamically with QAction::setText() via another action

Result: the text of QToolBar button won't change. QMenu entry works as expected.

What's expected: the text should change every time method executing QAction::setText() is being called