While writing layout engine testcases for background images I noticed that the "Common Border and Background" properties are not supported on all objects for which we claim full compliance in the compliance matrix on the website. The objects appear to include (this list may be incomplete): fo:character, fo:basic-link, fo:page-number, fo:page-number-citation. It also appears that while table-header/footer support borders they don't support backgrounds (at least don't support background images).
Correction: fo:basic-link does support backgrounds. It just doesn't work properly.
resetting P2 open bugs to P3 pending further review