Disable `GL_POLYGON_SMOOTH`.
Disabling GL_POLYGON_SMOOTH in vtkOpenGLContextDevice2D. It causes odd blending artifacts with Nvidia drivers on Linux when using Qt5 + OpenGL2.
Disabling GL_POLYGON_SMOOTH in vtkOpenGLContextDevice2D. It causes odd blending artifacts with Nvidia drivers on Linux when using Qt5 + OpenGL2.