Comment 3 for bug 623445

In trunk, as of 2010-11-25, the new "open holdings maintenance in a tab instead of a window" implementation seems to help avoid this problem; albeit perhaps in an annoying way. Once the item attribute editor from the first holdings maintenance tab is opened in a new window, you can't switch focus to a different tab.

You can use CTRL+Tab or File->New tab to open a new tab, search for another bib, and then open holdings maintenance for that bib - but the request for holdings seems to block until the item attribute editor window from the first holdings maintenance tab is closed.