grabeWidget & QTabWidget problem

[Uwe]

This is not really an answer to your question, but note that grabWidget is a suboptimal way to save plots. Better use QwtPlot::print(QPaintDevice&, ...) instead.

QwtPlot::print renders the plot to any rect in the resolution of your paint device + you can save it as vector graphics (f.e. Postscript, PDF, SVG). If you render to a QPrinter you can have Encapsulated Postscript with a much higher precision than on screen. If you render to a QPixmep you can have any format supported by QImageIO and if you render to a QPicture you can even have SVG. ( With Qt4 you can also render to PDF. )

Uwe