如何使用primefaces 3.5 blockUI阻止所有页面（p：layout）单击p：menu in p：layoutUnit（west）

Question

如何使用primefaces 3.5 blockUI 在p：layoutUnit（west）

中单击p：menu时阻止所有页面（p：layout）

main.xhtml

    <h:body>
        <p:layout fullPage="true">
            <p:layoutUnit gutter="0" collapseSize="0" id="topLayout" position="north" size="88">
                <h:form id="topForm">
                    <ui:include src="main_top.xhtml" /> 
                </h:form>
            </p:layoutUnit>
            <p:layoutUnit gutter="0" collapseSize="0" id="leftLayout" position="west" size="155" header="Main Menu">
                <h:form id="leftForm">
                    <ui:include src="main_left.xhtml" />
                </h:form>
            </p:layoutUnit>
            <p:layoutUnit gutter="0" collapseSize="0" id="centerLayout" position="center">
                <h:form id="centerForm" style="width:100%">
                    <ui:include src="#{LoxCtrl.gotoPage}" />
                </h:form>
            </p:layoutUnit>
        </p:layout>



    </h:body>

main_left.xhtml

        <p:menu>
            <p:menuitem value="Home" icon="ui-icon-home" actionListener="#{LoxCtrl.goToXHTMLTemplate('main_center.xhtml')}" update=":centerForm"/>
            <p:menuitem value="Staff Info." icon="ui-icon-person" actionListener="#{LoxCtrl.goToXHTMLTemplate('apps/staff_info/main.xhtml')}" update=":centerForm"/>
            <p:menuitem value="Leave History" icon="ui-icon-heart" actionListener="#{LoxCtrl.goToXHTMLTemplate('apps/leave/leave_his_main.xhtml')}" update=":centerForm"/>                                
            <p:menuitem value="Staff Leave History" icon="ui-icon-star" actionListener="#{LoxCtrl.goToXHTMLTemplate('apps/leave/staff_leave_his_main.xhtml')}" update=":centerForm"/>                                                
            <p:menuitem value="Board Bulletin" icon="ui-icon-clipboard" actionListener="#{LoxCtrl.goToXHTMLTemplate('apps/board_bulletin/board_bulletin.xhtml')}" update=":centerForm"/>
            <p:menuitem value="Logout" icon="ui-icon-locked" url="index.xhtml" />  

        </p:menu>