Sometimes QOpenGLWidget may be redirecting it's output to a framebuffer object rather than the frontbuffer, in which case the current thread's context render fbo is different from the widget's. Use the widget's desired fbo instead.
Sometimes QOpenGLWidget may be redirecting it's output to a framebuffer object rather than the frontbuffer, in which case the current thread's context render fbo is different from the widget's. Use the widget's desired fbo instead.