Selected edges disappear for certain viewing angles when using Parallel Projection

I found a better solution. It is simply to use:

this->SelectedActor->GetProperty()->SetRepresentationToWireframe();
this->SelectedActor->GetProperty()->LightingOff();
this->SelectedActor->GetProperty()->SetRenderLinesAsTubes(true);

Here is a quote from the documentation for SetRenderLinesAsTubes(): “The width of the line in pixels is controlled by the LineWidth attribute. May not be supported on every platform and the implementation may be half tubes, or something only tube like in appearance.”