Code from main or from QMainWindow differences

[qt_developer]

Hi all,

I have the next code and works properly:

#include <QApplication>
 
#include <QMainWindow>
#include <QVBoxLayout>
 
#include <QTreeView>
#include <QListView>
#include <QTableView>
 
#include <QStandardItemModel>
 
int main( int argc, char **argv )
{
  QApplication app( argc, argv );
 
  QMainWindow* mainWindow = new QMainWindow();
  QVBoxLayout* verticalLayout = new QVBoxLayout;
 
  QTreeView *tree = new QTreeView();
  QListView *list = new QListView();
  QTableView *table = new QTableView();
 
  verticalLayout->addWidget(tree);
  verticalLayout->addWidget(list);
  verticalLayout->addWidget(table);
 
  QWidget* window = new QWidget();
  window->setLayout(verticalLayout);
  mainWindow->setCentralWidget(window);
 
  QStandardItemModel model( 5, 2 );
  for( int r=0; r<5; r++ )
    for( int c=0; c<2; c++)
    {
      QStandardItem *item = new QStandardItem( QString("Row:%0, Column:%1").arg(r).arg(c) );
 
      if( c == 0 )
        for( int i=0; i<3; i++ )
        {
          QStandardItem *child = new QStandardItem( QString("Item %0").arg(i) );
          child->setEditable( false );
          item->appendRow( child );
        }
 
      model.setItem(r, c, item);
    }
 
  model.setHorizontalHeaderItem( 0, new QStandardItem( "Foo" ) );
  model.setHorizontalHeaderItem( 1, new QStandardItem( "Bar-Baz" ) );
 
  tree->setModel( &model );
  list->setModel( &model );
  table->setModel( &model );
 
  list->setSelectionModel( tree->selectionModel() );
 
 
  mainWindow->show();
 
  return app.exec();
}

#include <QApplication>

#include <QMainWindow>
#include <QVBoxLayout>

#include <QTreeView>
#include <QListView>
#include <QTableView>

#include <QStandardItemModel>

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

  QMainWindow* mainWindow = new QMainWindow();
  QVBoxLayout* verticalLayout = new QVBoxLayout;

  QTreeView *tree = new QTreeView();
  QListView *list = new QListView();
  QTableView *table = new QTableView();

  verticalLayout->addWidget(tree);
  verticalLayout->addWidget(list);
  verticalLayout->addWidget(table);

  QWidget* window = new QWidget();
  window->setLayout(verticalLayout);
  mainWindow->setCentralWidget(window);

  QStandardItemModel model( 5, 2 );
  for( int r=0; r<5; r++ )
    for( int c=0; c<2; c++)
    {
      QStandardItem *item = new QStandardItem( QString("Row:%0, Column:%1").arg(r).arg(c) );

      if( c == 0 )
        for( int i=0; i<3; i++ )
        {
          QStandardItem *child = new QStandardItem( QString("Item %0").arg(i) );
          child->setEditable( false );
          item->appendRow( child );
        }

      model.setItem(r, c, item);
    }

  model.setHorizontalHeaderItem( 0, new QStandardItem( "Foo" ) );
  model.setHorizontalHeaderItem( 1, new QStandardItem( "Bar-Baz" ) );

  tree->setModel( &model );
  list->setModel( &model );
  table->setModel( &model );

  list->setSelectionModel( tree->selectionModel() );


  mainWindow->show();

  return app.exec();
}

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The problem is when I put the same code inside a QMainWindow, a new window is opened but the widgets: tree, list and table, do not shown any information, they appear empty.

What's wrong?

Best regards.

---

Added after 10 minutes:

I have changed the line:

QStandardItemModel model( 5, 2 );

QStandardItemModel model( 5, 2 );

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by the line:

QStandardItemModel *model = new QStandardItemModel( 5, 2, this );

QStandardItemModel *model = new QStandardItemModel( 5, 2, this );

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And now works properly.

[amleto]

Do you know why that is?