By default check all in selcetItem with "MultipleAppearance.PICKLIST"

Hi,
I'm using smartgwt version 2.5.Pro with GWT 2.5.1

I use a multiple select item and set its multipleAppearance to PICKLIST and set its value map to a LinkedHashMap.

What i want is, when loading the form, getting all values checked by default.

I tried setDefaultValues() but it just fill the input text with values and doesn't check them on the drop down list !!