Diagram Scene Example - two overlapping ellipses

[d_stranz]

I doubt there is anything you can do if you must convert the path to a polygon. It is this conversion that is adding the extra line, as the docs say will happen. In order to create a single, complete polygon from two independent ellipses, it has to connect them.

You could easily solve this problem if you studied the Diagram Scene example and modified it to accept items derived from QAbstractGraphicsShapeItem instead of limiting it to polygon items only. Then you could add your path item without being forced to convert it to a polygon.