QChart in polar diagram, after setting the scope of the general can make the minimum point is displayed on the top of the icon, such as, range (180180), plus or minus in the top 180 in the polar diagram, 0 at the end, then, how to make zero displayed on the ICONS above, plus or minus 180 is shown in the below? Trouble bosses see after take time to solve, thank you very much, thank you!