I built some shapes which I draw in a preview panel.
Beside the preview panel is a form, where the user can change line-width, colors and so on.
Shape border is painted by draw(shape) and the filling of the shape is a separate task. Each one can be disabled separately.
I tried all cap- and join-styles, but I found no way to draw the shape that it looks like expected.
I attached 2 pictures to show, what I mean.
The preview pane has 2 shapes, and the buttons below the preview are RoundRectangle2D, where the user can change corner radius as well.