QSvgGenerator wrong line thickness

I'm using QSvgGenerator to rander a graphics-scene(see application.png) to a svg-file(see globale.svg).
The lines are created using QGraphicsPath with either a cosmetic pen or a linewidthF of 0.01.
I always get those fingerpaint lines.
Here a snip from my code:
void QtDra::svgPrint ( void )

{ QString filename=QFileDialog::getSaveFileName ( this, "svgname", QString(), "svg-files (*.svg)" ); if ( filename.isEmpty() ) return; QSvgGenerator generator; generator.setFileName(filename); generator.setSize(QSize(igw, igh)); generator.setViewBox(QRect(0, 0, igw, igh)); generator.setTitle(tr("bocad svg Drawing haha")); QPainter printerpainter( &generator ); render( &printerpainter ); }

Only for information, I'm using the same technique to print o0n a printer.

So what can I do to get something like wysiwig ?