StringCollection collection = new StringCollection();
collection.Add("Content 1");
collection.Add("Content 2");
collection.Add("Content 3");

ListSelectDecisionContext listSelectDecisionContext = new ListSelectDecisionContext(collection, "Content 2", "Dialog Title");

Decider oDecision = new Decider();
EnumDecisionReturn eAnswer = oDecision.Decide(listSelectDecisionContext);
if (eAnswer != EnumDecisionReturn.eOK)
{
    return false;
}

if (listSelectDecisionContext.AllowMultiSelect)
{
    StringCollection selectedEntries = listSelectDecisionContext.SelectedEntries;
}
else
{
    long index = listSelectDecisionContext.SelectedIndex;
    string strEntry = listSelectDecisionContext.SelectedEntry;
}