vtkOrientationMarkerWidget renders even if render window is not drawable
In vtkOrientationMarkerWidget::SetInteractive(int), this->Interactor->Render() is called without doing a check to see if the render window IsDrawable(). This causes various OpenGL errors if SetInteractive(int) is called before the render window is drawable (for instance at the time of widget construction if it is before the render window becomes drawable).
Easy fix to put an if statement right before the render call.