+ /* Section 4.4.2 (Attaching Images to Framebuffer Objects),
+ * subsection "Attaching Renderbuffer Images to a Framebuffer," of
+ * the OpenGL 3.1 spec says:
+ *
+ * "If a renderbuffer object is deleted while its image is
+ * attached to one or more attachment points in the currently
+ * bound framebuffer, then it is as if FramebufferRenderbuffer
+ * had been called, with a renderbuffer of 0, for each
+ * attachment point to which this image was attached in the
+ * currently bound framebuffer. In other words, this
+ * renderbuffer image is first detached from all attachment
+ * points in the currently bound framebuffer. Note that the
+ * renderbuffer image is specifically not detached from any
+ * non-bound framebuffers. Detaching the image from any
+ * non-bound framebuffers is the responsibility of the
+ * application.
+ */