Open Radar

 
Summary:
The table at https://developer.apple.com/graphicsimaging/opengl/capabilities/ lists an GL_APPLE_container_object_shareable extension for all renderers that support the core profile on both Mac OS X 10.8 and 10.7.4. It does not explain what it does, though.

Detail:
This extension is indeed supported on all Macs that I tested. For all other extensions, there is a link to the specification of that extension, but not for this one. The extension is not listed on http://www.opengl.org/registry/ . A search on developer.apple.com reveals the capabilities table and an API diffs file that explains when the symbols were added to the header (but not why). A search on Google gives the same results, plus some people printing out their OpenGL driver info, and me on Twitter, asking whether anyone knows more about this extension.

The extension also does not define any symbols in gl3ext.h, other than mentioning that it exists, so apparently it is active the whole time.

What I guess it does:
It seems to me that this extension allows me to share Vertex Array Objects between contexts, because a) VAOs are container objects, b) they are not normally shareable (thus the need for an extension), c) the extension says that container objects are or may become shareable and d) I've tried sharing VAOs on computers with Mac OS X 10.8 between different contexts (all core profile), and it has worked without any trouble.

If this is really the intended behavior of that extension, then it is extremely useful. The ARB's decision to not make VAOs shareable has certainly hindered me more than helped. I'd just like to know whether this intended behavior or whether I hit upon a bug in my graphics driver that makes it accidentally share VAOs.