Passing an object from one form to the other.

[wysota]

You mean something like this?

class A : public QWidget {
  Q_OBJECT
public:
  A(QWidget *parent = 0) : QWidget(parent){
    QVBoxLayout *l = new QVBoxLayout(this);
    le1 = new QLineEdit;
    le2 = new QLineEdit;
    QPushButton *pb = new QPushButton;
    connect(pb, SIGNAL(clicked()), SLOT(onClick()));
    l->addWidget(le1);
    l->addWidget(le2);
    l->addWidget(pb);
  }
public slots:
  void onClick(){
    QDialog dlg;
    QVBoxLayout *l = new QVBoxLayout(&dlg);
    QLabel *lab = new QLabel;
    l->addWidget(lab);
    lab->setText(le1->text()+" "+le2->text());
    dlg.exec();
  }
private:
  QLineEdit *le1, *le2;
};

class A : public QWidget {
  Q_OBJECT
public:
  A(QWidget *parent = 0) : QWidget(parent){
    QVBoxLayout *l = new QVBoxLayout(this);
    le1 = new QLineEdit;
    le2 = new QLineEdit;
    QPushButton *pb = new QPushButton;
    connect(pb, SIGNAL(clicked()), SLOT(onClick()));
    l->addWidget(le1);
    l->addWidget(le2);
    l->addWidget(pb);
  }
public slots:
  void onClick(){
    QDialog dlg;
    QVBoxLayout *l = new QVBoxLayout(&dlg);
    QLabel *lab = new QLabel;
    l->addWidget(lab);
    lab->setText(le1->text()+" "+le2->text());
    dlg.exec();
  }
private:
  QLineEdit *le1, *le2;
};

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The other "form" is the dialog in this case...