How to remove QwtPlot grey axes background and shadow?

[AhmedAlshawi]

I am using QwtPlot to plot a load of polygons, and I want the chart to look just like an image, rather than a chart. I have recently worked out how to remove the grey border behind the axes (A in attachment), and here is the code:

//set up QwtPlot
QwtPlot *plot = new QwtPlot;
//this code here changes the axis background from grey to white
QPalette pal = plot->palette();
pal.setColor(QPalette::Window, Qt::white);
plot->setPalette(pal);

//set up QwtPlot
QwtPlot *plot = new QwtPlot;
//this code here changes the axis background from grey to white
QPalette pal = plot->palette();
pal.setColor(QPalette::Window, Qt::white);
plot->setPalette(pal);

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However, I am trying to remove the shadow lines on the top and left of my QwtPlot (B in attachment). Does anyone know how to remove these?