Get behavior instance

function GetThisBehavior(inst)
{
    var i, len;
    for (i = 0, len = inst.behavior_insts.length; i < len; i++)
    {
        if (inst.behavior_insts[i] instanceof behaviorProto.Instance)
            return inst.behavior_insts[i];
    }
        return null;
};

See the official DragnDrop behavior.
"behaviorProto" could be changed to specific behavior.