Hello.in this code, the QMenu and the QAction work well.but the newact can not use from the setStatusTip("Open a new file"); thank you.

Qt Code: 
  1. #ifndef WIDGET_H
  2. #define WIDGET_H
  3. #include <QtWidgets>
  4. class widget:public QMainWindow
  5. {public:
  6.    widget();
  7.    void createmenu();
  8.    void createaction();
  9. private:
  10.    QTextEdit*text;
  11.    QMenu*filemenu;
  12.    QAction*newact;
  13. };
  14. #endif // WIDGET_H
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Qt Code: 
  1. #include <QtWidgets>
  2. #include "widget.h"
  3. widget::widget()
  4. {text=new QTextEdit;
  5. resize(250,250);
  6. setCentralWidget(text);
  7. createaction();
  8. createmenu();
  9. }
  10. void widget::createmenu()
  11. {filemenu=menuBar()->addMenu(tr("File"));
  12. filemenu->addAction(newact);
  13. }
  14. void widget::createaction()
  15. {
  16.     newact=new QAction(tr("&New"),this);
  17. newact->setShortcut(QKeySequence::New);
  18. newact->setStatusTip("Open a new file");
  19. }
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Qt Code: 
  1. #include "widget.h"
  2. #include <QtWidgets>
  3. int main(int argv,char*argc[])
  4. {
  5.     QApplication app(argv,argc);
  6.     widget window;
  7.     window.show();
  8.     return app.exec();
  9. }
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