Comment 1 for bug 912706

According to https://bugzilla.mozilla.org/show_bug.cgi?id=281219 the "Show items that contain" is for Newsgroup use but disabled for IMAP rather than hidden. In my opinion a minor bug that may cause confusion but the implication from the bug report is that the Subscribe dialog has been designed that way. Bug report ongoing for 14+ years so an issue that may never be fixed.