adjustSize() is not up to date when widget is within a QScrollArea

if widget is not set to be resizable in the scroll area, and child widgets are being added to it in a layout, then adjustSize will get a wrong size and make it too small.

Following snippet demonstrates the problem:

#include <QtGui>

class CustomWidget: public QWidget{
Q_OBJECT

public:
CustomWidget(QWidget *parent = 0, Qt::WindowFlags f = 0) : QWidget(parent, f)

{ layoutB = new QVBoxLayout(); setLayout(layoutB); }

public slots:
void addButton()

{ layoutB->addWidget( new QPushButton("Sample") ); adjustSize(); } private: QVBoxLayout *layoutB; }

;

#include "main.moc"

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

QWidget *mainWidget = new QWidget();
QVBoxLayout layoutA;
mainWidget->setLayout(&layoutA);
QPushButton *pushButton = new QPushButton("Add a widget");
layoutA.addWidget(pushButton);
QScrollArea *scrollArea = new QScrollArea(mainWidget);
CustomWidget *custom = new CustomWidget(scrollArea);
scrollArea->setWidget(custom);
layoutA.addWidget(scrollArea);

QObject::connect( pushButton, SIGNAL(pressed()),
custom, SLOT(addButton()) );

mainWidget->resize( 300, 400 );
mainWidget->show();

return app.exec();
}