Created attachment 401462 [details] show the menu Have a look at attached screenshot. One selection can just have one alignment, therefore this must be a radiobox.
Yeah, they should be. The menu building infrastructure however currently doesn't have a distinction between checkboxes or radiobuttons, though the menu rendering infrastructure does
Submitted a patch upstream as http://qa.openoffice.org/issues/show_bug.cgi?id=110565 to change the alignment (and anchor and cursor selection mode) entries to checkboxes, build on infrastructure that will only be available in 3.3. So closing->upstream.