Try to test this:

Qt Code: 
  1. #include <QtGui>
  2. #include <QLabel>
  3.  
  4. //! [main function]
  5. int main(int argc, char *argv[])
  6. {
  7.     QApplication app(argc, argv);
  8.  
  9.     QLabel widget("TEST");
  10.     QFont f = widget.font();
  11.     f.setPointSize(100);
  12.     widget.setFont(f);
  13.     widget.setWindowFlags(Qt::WindowFlags(Qt::FramelessWindowHint));
  14.     widget.setAttribute(Qt::WA_TranslucentBackground);
  15.     widget.show();
  16.  
  17.     return app.exec();
  18. }
  19. //! [main function]
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