I have a peculiar application whereby my post edit screen is presented in a thickbox window, instead of being the top.document.
When I click the "Attach" button located in the Attachments metabox on the post edit screen, that brings up the "Attach a file" thickbox containing the media-upload interface, within the thickbox that is already existing and holding my post edit screen.
So now I have a top.document, a first thickbox containing the post edit screen, and a second thickbox (within the first thickbox) containing the media-upload interface.
Clicking "attach" in the media-upload interface pops up the "Attached!" message, but the attachment is not actually showing up in the Attachments metabox on the post edit screen, which exists as an upper level iframe instead of all the way at top.document.
I replaced all top.document references in attachments.js with parent.document but that did not fix the problem. I'm looking at theparent=jQuery(this).parent().parent().parent() and thinking the trouble may be in there someone, but the js here is a little over my head.