Setting up different printers on system i can get page sizes only from the default one in the case of using a code like the following (from kipi printwizard):
QList<QPrinterInfo>::iterator it;
//m_printerList = QPrinterInfo::availablePrinters ();

for ( it = d->m_printerList.begin();
it != d->m_printerList.end(); ++it )
{
if (it->printerName () == text)

{ kDebug() << "Choosen printer: " << it->printerName (); if (d->m_printer) delete d->m_printer; d->m_printer = new QPrinter(*it); }

}
...
void Wizard::pagesetupclicked()
{
if (d->m_pDlg)
delete d->m_pDlg;
d->m_pDlg = new QPageSetupDialog (d->m_printer, this);
int ret = d->m_pDlg->exec();
if ( ret == QDialog::Accepted )

{ pagesetupdialogexit(); }

}