ivaynberg/select2 — pull request #758 by jpurcell001 (2013-01-25 20:46:00+00:00)
Title: Highlighting broken with multiple: true and closeOnSelect: false

The index of the current choice being moused-over was being passed into highlight. However, in `highlightUnderEvent`, the index was being calculated against all .select2-result choices, which included selected options. In `highlight`, the index was being calculated against only visible elements.

An alternate fix might be:
`var choices = this.results.find('.select2-result:visible');`
since this seems to duplicate the logic in `highlight`.

The symptoms for this seemed similar to #348, but that fix is still on master; I think the implementation of `highlight` has evolved since that fix, which may have caused the issue to resurface.