Found solution now for sure:
QTest::keyClick(win, Qt::Key_F, Qt::AltModifier,500);
QTest::keyClicks(win->focusWidget(),"blah");
QTest::keyClick(win, Qt::Key_W, Qt::AltModifier,500);
QTest::keyClicks(win->focusWidget(),"blah2");
Last parameter is delay and It is necessary (You should test it).