I tried changing the code in the demo (polardemo) that comes with qwtpolar and it still doesn't work. In the Plot constructor I changed this line in the code
setScale(QwtPolar::Radius,radialInterval.minValue( ), radialInterval.maxValue())
which sets it up to autoscale the division lines to
setScale(QwtPolar::Radius,radialInterval.minValue( ), radialInterval.maxValue(),8) but the scale division lines don't change, they stay at the autoscale division line values. I also tried 1.0 and 5.0 with no change. This is using the code that comes with qwtpolar as an example. I'm starting to firmly believe it's a bug. I mean it still does it when using code that supposedly works perfectly and changing one parameter, that should turn off autoscale and make it change to a user set value. Where does one report a bug?