Fix bug of window closing and reshowing

Sine Striker

2024-02-23 6c0043c1e3d97398828fbd56448f1cd8ee201e66

 examples/mainwindow/mainwindow.h

@@ -30,6 +30,8 @@
protected:
    bool event(QEvent *event) override;

    void closeEvent(QCloseEvent *event) override;

private:
    void installWindowAgent();
    void loadStyleSheet(Theme theme);