QDockWidget title is not displayed correctly when stylesheet is used

QDockWidget title text is not displayed correctly when stylesheet is used:

setStyleSheet("QDockWidget::title {"
                  "background: yellow;"
                  "}"
                  );

If the titlebar is set to vertical position only few letters of title text is shown.
In horizontal alignment text gets overlapped with the buttons if the text is long enough.

Please, see the attached picture and the example application.