Hi..
I have observed that when the multiselect property is switched ON/OFF dynamically, then after the multiselect shows trouble. The newly selected items wond show, though they marked as selected in the pull down list, or some times, it does not list items, or even some times the iner text lineposition moves up or down and not alin with the combobox.
Given a sample at
http://jsfiddle.net/wrn36qkz/
By default teh multiselect is OFF, click teh button to select few. Then using teh other button change it to Single selection mode. Again change it to multi select using teh button and try select items and see.
Please let me know how can we correct this issue?