OpenImageIO/oiio — pull request #856 by lgritz (2014-05-16 01:12:25+00:00)
Title: oiiotool --over should set output display window to union, not fg

I hadn't noticed a problem before because fg and bg are usually the same
size. But if they differ, it seems likely that it's a small element
being put overtop a fixed background, so setting the output's display
("full") window to the fg is not what you want.