message: Ensure we set the format for the OpenGL context
  Some GPUs are fussier than others, this fixed chart rendering on Intel.
diff: @@ -65,6 +65,7 @@ void XrdVtkPlot::generatePlot(
  widget->SetRenderWindow(renderWindow);
  // Hackish, but at least it won't leak
  widget->setAttribute(Qt::WA_DeleteOnClose);
  + widget->setFormat(QVTKOpenGLWidget::defaultFormat());
  vtkNew<vtkContextView> view;
  view->SetRenderWindow(renderWindow);
  view->GetRenderer()->SetBackground(1.0, 1.0, 1.0);
  