将事件/操作连接到 QPlainTextEdit

我有一个包含QPlainTextEdit的QTabWidget。我已经设法向 QTabWidget 添加了操作，以便每当打开新选项卡时，都会在新选项卡中添加新的 QPlainTextEdit。 请参阅代码。

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QPlainTextEdit>
#include <QMessageBox>
#include <QAction>
#include <QTextCursor>
#include <iostream>
#include <QKeyEvent>
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    setWindowTitle("Tilde");
    current_tab = 1;
    on_action_New_triggered();
    ui->tabWidget->setTabsClosable(true);
}
MainWindow::~MainWindow()
{
    delete ui;
}
void MainWindow::on_action_New_triggered()
{
    QString newTab = "Tab " + QString::number(current_tab);
    ui->tabWidget->addTab(new QPlainTextEdit, newTab);
    ui->tabWidget->setCurrentIndex(current_tab - 1);
    current_tab++;
    editor = qobject_cast<QPlainTextEdit *>(ui->tabWidget->currentWidget());
    editor->setFocus();
    /*connect(editor->document(), SIGNAL(cursorPositionChanged(QTextCursor)),
            this, SLOT(on_editor_cursorPositionChanged()));*/
}
void MainWindow::on_actionNew_document_triggered()
{
    on_action_New_triggered();
}
void MainWindow::on_action_Exit_triggered()
{
    QMessageBox msg;
    msg.addButton(QMessageBox::Yes);
    msg.addButton(QMessageBox::No);
    msg.setText("Exit program?");
    int selection = msg.exec();
    if (selection == QMessageBox::Yes)
        qApp->exit(0);
}
// highlight current line
void MainWindow::on_editor_cursorPositionChanged()
{
    QTextEdit::ExtraSelection highlight;
    highlight.cursor = editor->textCursor();
    highlight.format.setProperty(QTextFormat::FullWidthSelection, true);
    highlight.format.setBackground( QColor(240, 246, 217) );
    QList<QTextEdit::ExtraSelection> extras;
    extras << highlight;
    editor->setExtraSelections(extras);
}

注释的代码给出编译器错误：

QMetaObject：：connectSlotsByName： 没有匹配的信号 on_editor_cursorPositionChanged（）

我已经在头文件中添加了该函数。

头文件：

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QPlainTextEdit>
#include <QTextCursor>
namespace Ui
{
    class MainWindow;
}
class MainWindow : public QMainWindow
{
    Q_OBJECT
public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
private slots:
    void on_action_New_triggered();
    void on_actionNew_document_triggered();
    void on_action_Exit_triggered();
    void on_editor_cursorPositionChanged();
private:
    Ui::MainWindow *ui;
    QPlainTextEdit *editor;
    qint8 current_tab;
};
#endif // MAINWINDOW_H