STemWin will not display large ellipses properly

[t.albrecht]

When drawing large ellipses, STemWin will not display them as an ellipse, but instead as this zigg-zagged-pattern, which you can see in the attached picture.

Has anyone ever encountered a similar issue? Is there any kind of support for these kind of bug from ST side?

GUI_AA_FillEllipse(200, 400, 200, 400);