A checkbox on a panel in a panel stack can be cleared when switching panels. This happens when the panel stack and command buttons are all contained in the same form.

<ice:form partialSubmit="true" id="innerFrame1">
<ice:commandButton value="Show One" action="#{checkboxclear.showOne}"/>
        <ice:commandButton value="Show Two" action="#{checkboxclear.showTwo}" />

         <ice:panelStack id="templatePanelStack"
                        styleClass="componentContentPanelStack"
                        selectedPanel="#{checkboxclear.selectedPanel}">



             <ice:panelGroup id="one">
                  <ice:outputText value="Checkbox value is"/>
                  <ice:outputText value="#{checkboxclear.value}"/>
             </ice:panelGroup>
             <ice:panelGroup id="two">
                 <ice:outputText value="Check Box:"/>
                 <ice:outputText value="#{checkboxclear.value}"/>

                 <ice:selectBooleanCheckbox value="#{checkboxclear.value}" partialSubmit="true"/>

             </ice:panelGroup>
         </ice:panelStack>
     </ice:form>