aboutdialog.h:
 
#ifndef ABOUTDIALOG_H
#define ABOUTDIALOG_H
#include <QDialog>
namespace Ui {
    class AboutDialog;
}
class AboutDialog : public QDialog {
    Q_OBJECT
public:
    AboutDialog(QWidget *parent = 0);
    ~AboutDialog();
protected:
    void changeEvent(QEvent *e);
private:
    Ui::AboutDialog *ui;
private slots:
    void on_closeBtn_clicked();
};
#endif // ABOUTDIALOG_H
 
大家看哈 怎么处理这个错误!谢谢了!