We just discovered this too. We can get Ajax editing on some course pages only for one item - the news forum, and only if the news forum is placed at the very top of topic '0." Anything below that, including all remaining sections, use the non-Ajax icons and method. Strangely enough, this only occurs in some courses. At first I thought it had something to do with Ajax marking block (though it's a default block in all courses), but now I have no idea. I can't find anything out of sorts or different about these courses, and they were all created at differnt times. Running debug mode, I got messages like:
ERRO 2734ms (+78) 8:53:23 PM:globalCannot find updateButton for module-12190,
Init resource, NO ID FOUND!
Firebug shows: uncaught exception: [Exception... "Component returned failure code: 0x80004003 (NS_ERROR_INVALID_POINTER) [nsIDOMHTMLElement.appendChild]" nsresult: "0x80004003 (NS_ERROR_INVALID_POINTER)" location: "JS frame :: http://internethomeschool.net/lib/ajax/section_classes.js :: anonymous :: line 650" data: no] Line 0
IE shows: invalid pointer error for course/view.pgp?id=xxx