defining a widget from the ui file

[ravas]

I'm trying to figure out how I can use the mouseReleaseEvent of the textEdit in the simple notepad example.
http://doc.qt.io/qt-5/gettingstartedqt.html

I understand how to set it up for the Notepad class...
but I can't figure out how to access <widget class="QTextEdit" name="textEdit"> from the ui file.

The closest I have come created a second QTextEdit,
when I tried to mimic the Notepad class.

notepad.h

#ifndef NOTEPAD_H
#define NOTEPAD_H
 
#include <QMainWindow>
#include <QTextEdit>
 
namespace Ui {
class Notepad;
class textEdit;
}
 
class Notepad : public QMainWindow
{
    Q_OBJECT
 
public:
    explicit Notepad(QWidget *parent = 0);
    ~Notepad();
 
private slots:
    void on_quitButton_clicked();
 
private:
    Ui::Notepad *ui;
};
 
class textEdit : public QTextEdit
{
    Q_OBJECT
 
public:
    textEdit(QWidget *parent);
 
private slots:
 
    void mouseReleaseEvent(QMouseEvent *event);
 
};
 
#endif // NOTEPAD_H

#ifndef NOTEPAD_H
#define NOTEPAD_H

#include <QMainWindow>
#include <QTextEdit>

namespace Ui {
class Notepad;
class textEdit;
}

class Notepad : public QMainWindow
{
    Q_OBJECT

public:
    explicit Notepad(QWidget *parent = 0);
    ~Notepad();

private slots:
    void on_quitButton_clicked();

private:
    Ui::Notepad *ui;
};

class textEdit : public QTextEdit
{
    Q_OBJECT

public:
    textEdit(QWidget *parent);

private slots:

    void mouseReleaseEvent(QMouseEvent *event);

};

#endif // NOTEPAD_H

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notepad.cpp

#include "notepad.h"
#include "ui_notepad.h"
 
Notepad::Notepad(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::Notepad)
{
    ui->setupUi(this);
}
 
Notepad::~Notepad()
{
    delete ui;
}
 
void Notepad::on_quitButton_clicked()
{
    qApp->quit();
 
}
 
textEdit::textEdit(QWidget *parent) :
    QTextEdit(parent){}
 
void textEdit::mouseReleaseEvent(QMouseEvent *event)
{
    copy();
}

#include "notepad.h"
#include "ui_notepad.h"

Notepad::Notepad(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::Notepad)
{
    ui->setupUi(this);
}

Notepad::~Notepad()
{
    delete ui;
}

void Notepad::on_quitButton_clicked()
{
    qApp->quit();

}

textEdit::textEdit(QWidget *parent) :
    QTextEdit(parent){}

void textEdit::mouseReleaseEvent(QMouseEvent *event)
{
    copy();
}

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main.cpp

#include "notepad.h"
#include <QApplication>
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Notepad w;
    w.show();
    textEdit txt(&w);
    txt.show();
 
    return a.exec();
}

#include "notepad.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Notepad w;
    w.show();
    textEdit txt(&w);
    txt.show();

    return a.exec();
}

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Qt 5.4.1 (windows 7)