<h:form><a4j:region>
<h:inputText value="#{myBean.keyword}">
<a4j:support event="onchange" reRender="results" eventsQueue="search" oncomplete="initResults();" />
</h:inputText>
</a4j:region>
</h:form>

<a4j:form rerender=results" reRender="results" eventsQueue="search" oncomplete="initResults();"><a4j:region>
<h:inputText value="#{myBean.keyword}"/>
</a4j:region>
</h:form>

<a4j:region>
<h:form>
<a4j:support event="onsubmit" reRender="results" eventsQueue="search" oncomplete="initResults();" />
<h:inputText value="#{myBean.keyword}"/>
</h:form>
</a4j:region>

<h:selectOneMenu value="#{myBean.selectedMetaCategory}" onchange="this.form.submit();">
  <a4j:support ...
  <f:selectItems value="#{myBean.metaSelectItems}"/>
</h:selectOneMenu>

<a4j:region>
<a4j:form onsubmit="reRenderResults();">
<h:inputText value="#{myBean.keyword}"/>
</a4j:form>
<a4j:jsFunction name="reRenderResults" reRender="results" eventsQueue="search" oncomplete="initResults();" />
</a4j:region>