все решено
QApplication a(argc, argv);
QTextCodec *localcoder = QTextCodec::codecForName("UTF-8");
QTextCodec::setCodecForTr(localcoder);
QTextCodec::setCodecForCStrings(localcoder);
QTextCodec::setCodecForLocale(localcoder);
MainWindow *GenForm = new MainWindow;
QFont serifFont("DejaVu Sans", 10, QFont::Bold);
GenForm->setFont(serifFont);
GenForm->runAllThreads();