%%%%%%%%%%%%%%%%%%%%%%%%%    layout.h

#include <QWidget>
#include "input.h"
    .
    .
#include "disegna.h"

class Layout : public QWidget
{
    Q_OBJECT
public:

    Layout(QWidget* parent=0);
    ~Layout(){}

private:

    Input* input;
    .
    .
    .
    disegna* dis;

%%%%%%%%%%%%%%%%%%%%%%%%%    layout.cpp

Layout::Layout(QWidget *parent): QWidget(parent){


    input = new Input;
    .
    .
    .
    dis = new disegna;

    QGridLayout* view = new QGridLayout(this);

    view->addWidget(input,0,0,1,1);
    .
    .
    .
    view->addWidget(dis,1,1,1,1);

    this->setLayout(view);

%%%%%%%%%%%%%%%%%%%%%%%%%   disegna.h
#ifndef disegna_H
#define disegna_H

#include <QGraphicsScene>
#include <QGraphicsView>

class disegna: public QWidget
{
    Q_OBJECT

private:

    QGraphicsScene scene;

public:

    disegna (QWidget *parent = 0);
};
#endif // disegna_H

%%%%%%%%%%%%%%%%%%%%%%%%%   disegna.cpp

#include "disegna.h"
#include <QGraphicsScene>
#include <QGraphicsView>


disegna::disegna(QWidget *parent) : QWidget(parent) {

    scene.addText("Hello, world!");

    QGraphicsView view(&scene);
    view.show();


};