botão fechar dentro do <p:overlayPanel />

<h:panelGrid columns="4" cellspacing="7" width="100%"
	styleClass="paineis">
	<p:commandButton id="btnOverlayPanel" value="Item" type="button"
		style="height: 37px;" />
	<p:overlayPanel id="selectItemPanel" for="btnOverlayPanel"
		hideEffect="fold" dynamic="true" showEffect="fold">
		<p:multiSelectListbox value="#{itemMB.item.nome_item}" id="Item"
			required="true" effect="slide" header="Categoria">
			<f:selectItems value="#{menuMultSelectList.categories}" />
		</p:multiSelectListbox>
		<br />
		<p:commandButton action="#{itemMB.item.trocaIcone}"
			icon="ui-icon-check" process="@form:selectItemPanel"
			update="itemTexto itemImagem"
			/>// COMO FAZ PARA FECHAR O OVERLAYPANEL DEPOIS DE EXECUTAR O ACTION?
	</p:overlayPanel>
</h:panelGrid>