QTabwidgets are not accessible with Screenreaders

When using the QTabwidget Control in an QT application a Screenreader such as Jaws (www.freedomscientific.com) or NVDA (www.nvda-project.org) doesn't read the current selected tab. This is allso true, if setAccessibleName and setAccessibleDescription have been used to setup accessibility information for the tabs. The bug prevents screenreader users from using any QT application taht uses the QTabwidget. Tabwidgets should use the captions of tabs as accessibleName if the information has not been set programmatically.