How to develop a multi-gui application "alternative for the stacked widget "

[sliverTwist]

Well at first i created in my project a new Qt Designer Form Class which is a widget called widget2 that created an new .ui/.cpp/.h files then i wrote this code in my mainwindow wich contain a QStackedWidget

ui->stackedWidget->setCurrentIndex(0);
    Widget2 * newWidget2 = new Widget2;
    ui->stackedWidget->addWidget( newWidget2 );

ui->stackedWidget->setCurrentIndex(0);
    Widget2 * newWidget2 = new Widget2;
    ui->stackedWidget->addWidget( newWidget2 );

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but i doesn't do the job