Program: 70788
Project: 70788
Buggy source:
@Override public void render(Renderer renderer,int flags){
  RenderProps props=getRenderProps();
  if (props == null) {
    return;
  }
  if (!(renderer instanceof GL2Viewer)) {
    return;
  }
  GL2Viewer viewer=(GL2Viewer)renderer;
  GL2 gl=viewer.getGL2();
  gl.glPushMatrix();
  Shading shading=props.getShading();
  if (shading != Shading.NONE) {
    renderer.setFaceColoring(props,isSelected());
  }
  if (props.getFaceStyle() != Renderer.FaceStyle.NONE) {
    Shading savedShadeModel=renderer.getShading();
    if (shading == Shading.NONE) {
      renderer.setColor(props.getFaceColorF(),isSelected());
    }
    renderer.setShading(shading);
    if (props.getDrawEdges()) {
      gl.glEnable(GL2.GL_POLYGON_OFFSET_FILL);
      gl.glPolygonOffset(1f,1f);
    }
    drawFaces(gl,renderer,props);
    if (props.getDrawEdges()) {
      gl.glDisable(GL2.GL_POLYGON_OFFSET_FILL);
    }
    renderer.setShading(savedShadeModel);
  }
  if (!renderer.isSelecting()) {
    if (props.getBackColorF() != null) {
      gl.glLightModelf(GL2.GL_LIGHT_MODEL_TWO_SIDE,1f);
    }
  }
  if (props.getDrawEdges()) {
    float savedLineWidth=renderer.getLineWidth();
    Shading savedShadeModel=renderer.getShading();
    renderer.setLineWidth(props.getLineWidth());
    if (props.getLineColor() != null && !renderer.isSelecting()) {
      renderer.setShading(Shading.NONE);
      renderer.setLineColoring(props,isSelected());
    }
    if (useVertexColouring && !renderer.isSelecting()) {
      renderer.setShading(Shading.GOURAUD);
    }
 else {
      renderer.setShading(Shading.FLAT);
    }
    drawEdges(gl,props);
    renderer.setLineWidth(savedLineWidth);
    renderer.setShading(savedShadeModel);
  }
  gl.glPopMatrix();
}

Fixed version (ground truth):
@Override public void render(Renderer renderer,int flags){
  RenderProps props=getRenderProps();
  if (props == null) {
    return;
  }
  if (!(renderer instanceof GL2Viewer)) {
    return;
  }
  GL2Viewer viewer=(GL2Viewer)renderer;
  GL2 gl=viewer.getGL2();
  gl.glPushMatrix();
  Shading shading=props.getShading();
  if (shading != Shading.NONE) {
    renderer.setFaceColoring(props,isSelected());
  }
  if (props.getFaceStyle() != Renderer.FaceStyle.NONE) {
    Shading savedShadeModel=renderer.getShading();
    if (shading == Shading.NONE) {
      renderer.setColor(props.getFaceColorF(),isSelected());
    }
    renderer.setShading(shading);
    if (props.getDrawEdges()) {
      gl.glEnable(GL2.GL_POLYGON_OFFSET_FILL);
      gl.glPolygonOffset(1f,1f);
    }
    drawFaces(gl,renderer,props);
    if (props.getDrawEdges()) {
      gl.glDisable(GL2.GL_POLYGON_OFFSET_FILL);
    }
    renderer.setShading(savedShadeModel);
  }
  if (!renderer.isSelecting()) {
    if (props.getBackColorF() != null) {
      gl.glLightModelf(GL2.GL_LIGHT_MODEL_TWO_SIDE,1f);
    }
  }
  if (props.getDrawEdges()) {
    float savedLineWidth=renderer.getLineWidth();
    Shading savedShadeModel=renderer.getShading();
    renderer.setLineWidth(props.getLineWidth());
    if (props.getLineColor() != null && !renderer.isSelecting()) {
      renderer.setShading(Shading.NONE);
      renderer.setLineColoring(props,isSelected());
    }
    if (useVertexColouring && !renderer.isSelecting()) {
      renderer.setShading(Shading.PHONG);
    }
 else {
      renderer.setShading(Shading.FLAT);
    }
    drawEdges(gl,props);
    renderer.setLineWidth(savedLineWidth);
    renderer.setShading(savedShadeModel);
  }
  gl.glPopMatrix();
}