Pyqtgraph solid fill ROI

Question

I have some code to add a lineout ROI to a pyqtgraph PlotItem

    self.roi = pg.ROI([c, -x.ptp()/2], [self.pixsize, x.ptp()],pen=pg.mkPen('r',width=1))
    self.roi.addScaleHandle([0.5, 0.9], [0.5, 0.5])
    self.roi.addRotateFreeHandle([0.5, 0.75], [0.5, 0.5])
    self.mainImage.addItem(self.roi)
    self.roi.setZValue(10)  # make sure ROI is drawn above image

This functions and puts an ROI on the image.

However the ROI is formed as a rectangle with very thin lines at the edges, which are difficult to precisely click. Is it possible to draw the ROI as a solid object with filled centre?

Thanks in advance