#include <QApplication>
#include <QDebug>
#include <QWidget>
#include <QTextEdit>
#include <QLineEdit>
#include <QPushButton>
#include <QBoxLayout>
#include <QLabel>

class Widget:public QWidget{
    QPushButton* but;
    Widget* other;
public:
    Widget();
    void setother(Widget& w);
    void buttext(const char* text);
    void click();
};

Widget::Widget() : other(NULL)
{
     but = new QPushButton(this);
     QVBoxLayout lay;
     lay.addWidget(this);
     QObject::connect(but, &QPushButton::clicked, this, &Widget::click);
 }

void Widget::setother(Widget& w)
{
    other=&w;
}

void Widget::buttext(const char* text)
{
    but->setText(text);
}

void Widget::click()
{
    this->hide();
    if (other) {
        other->show();
    }
}

int main(int argc,char** argv)
{
    QApplication app(argc,argv);

    Widget w1,w2;
    w1.buttext("w1.but");
    w2.buttext("w2.but");
    w1.setother(w2);
    w2.setother(w1);

    w1.show();

    return app.exec();
}