use ‘&&’ in MXML

see ref:Flex tip: conditions like ‘&&’ in MXML


<BetterFormItem label="{Util.geti18nText(this,'roles')}"
width="100%"
id="role_gateway_id"
key="rules"
includeInLayout="{raciGridPerformersRaci.dataProvider.length>0 &amp;&amp; raciGridPerformersRaci.selectedItem.@type_id =='ROLE'}"
visible="{raciGridPerformersRaci.dataProvider.length>0 &amp;&amp; raciGridPerformersRaci.selectedItem.@type_id =='ROLE'}"
>
</BetterFormItem>