'Ctrl+Tab'

def tab_navigate(self, delta=1):

    if ((delta > 0) and (self.currentIndex() == (self.count() - 1))):
        index = (delta - 1)
    elif ((delta < 0) and (self.currentIndex() == 0)):
        index = (self.count() + delta)
    else:
        index = (self.currentIndex() + delta)
    self.setCurrentIndex(index)
