This is an extension for the RichUI Plugin Accordion to allow for pre-expansion of a selected section using an expanded boolean attribute.

Configuration

You need to tell the RichUI plugin that we have a replacement renderer for accordion (also see grails-app/conf/Config.groovy):

// richui config addition
richui.accordionItemRenderer="ExpandableAccordionItemRenderer"

Renderer

Drop into src/groovy

GSP example

<resource:accordion skin="custom" />
<div id="summary_left">
    <div class="country_select">
        <div class="panel_head2">Select Country</div>
        <br /><br />
        <richui:accordion>
            <g:each in="${regionInstanceList}" status="i" var="regionInstance">
                <richui:accordionItem id="${regionInstance.regionName}" caption="${regionInstance.regionName}" 
                  expanded="${regionInstance.regionName == selectedRegionName}">
                    <g:each var="rc" in="${regionInstance.countries}">
                        <g:set var="countryId" value="${rc.country.id}"/>
                        <g:link controller="${controller}" action="${action}" params="[country_id:countryId]">
                            ${rc.country?.encodeAsHTML()}
                        </g:link><br/>
                    </g:each>                       
                </richui:accordionItem>
            </g:each>
        </richui:accordion>             
    </div>
</div>  

In this case the controller has used a query string parameter to pre-expand a section if the user has selected one...

} else if(params.regionName) {
    selectedRegionName = params.regionName