RadCombobox always fire SelectedIndexChanged event when multiple items are selected (checked)

[Sheng]

I'm using Q2 2015 (2015.2.826.45). My web form has RadCombobox with "CheckBoxes" set to true. I want SelectedIndexChanged fired only when the selected (checked) items are changed. However, I found when multiple items (3 or above) are selected, the SelectedIndexChanged event are always fired after postback. I think this is a bug. Please advise.

[Sheng]

Just found if setting CheckedItemsTexts="DisplayAllInInput" the event can fire properly.