Setting the scrollHeight and scrollWidth of a surrounding panelGroup causes the selectInputText drop down list to render over top and somewhat above the component itself. Here is the code along with a test case and screen shot.

<ice:panelGroup scrollHeight="200px" scrollWidth="500px">
<br />
.............

<ice:panelGroup>
<ice:selectInputText rows="6" width="300" listVar="city"
valueChangeListener="#{autoCompleteBean.updateList}"
listValue="#{autoCompleteBean.list}">
<f:facet name="selectInputText">
<ice:panelGrid columns="3"
columnClasses="cityCol,stateCol,zipCol">
<ice:outputText value="#{city.city}" />
<ice:outputText value="#{city.state}" />
<ice:outputText value="#{city.zip}" />
</ice:panelGrid>
</f:facet>
</ice:selectInputText>
</ice:panelGroup>
</ice:panelGroup>