JSF/PrimeFaces: Selection based visibility - ajax

Question

I want to show / now show (for example) a text, based on a radio selection.
In an ajax style, no roundtrip to server.
How do I have to do this with JSF/PrimeFaces?
<h:outputText value="Show some stupid Text." id="testShowText" />
<p:selectOneRadio id="testRadio" widgetVar="testRadio" value="True" layout="grid" columns="1">
<f:selectItem itemLabel="Show Text" itemValue="True"/>
<f:selectItem itemLabel="Do NOT show Text" itemValue="False"/>
</p:selectOneRadio>
UPDATE
I managed it in my test this way, but I am not sure, if this is the "best practice", I have some doubts; do I really need a managed bean for this?:
First I created a Bean to store the selected value:
import javax.faces.bean.ManagedBean;
import javax.faces.bean.ViewScoped;
#ManagedBean
#ViewScoped
public class ShowTextBean {
private boolean showBool = false;
private String showString = "False";
public ShowTextBean() {
}
public boolean isShowBool() {
return showBool;
}
public void setShowBool(boolean showBool) {
this.showBool = showBool;
}
public String getShowString() {
return showString;
}
public void setShowString(String showString) {
this.showString = showString;
}
}
Then I changed the Facelets Code to:
<p:panel id="testShowTextPanel" style="display: #{showTextBean.showString eq 'False' ? 'none' : 'block'} ">
<h:outputText value="Show some stupid Text." id="testShowText"/>
</p:panel>
<p:selectOneRadio id="testRadio" widgetVar="testRadio" value="#{showTextBean.showString}" layout="grid" columns="1">
<f:selectItem itemLabel="Show Text" itemValue="True"/>
<f:selectItem itemLabel="Do NOT show Text" itemValue="False"/>
<p:ajax update="testShowTextPanel" />
</p:selectOneRadio>