Lets say the ComboBox has selected item with index N then If you call set method of list with index K, where K <= N then ComboBox autoselects next item (if it possible) after this action.

And if you call remove method of list with index K, where K <= N, then ComboBox autoselects previous item.

I expect that if I just change item, i.e. use set method of list, then comboBox doesn't change selection (if it isn't selected item).

more information on this question:
http://stackoverflow.com/questions/26144930/combobox-strange-behaviour-javafx-8