How to assign a value to the page variable to enable partial page rendering

Question

This is part of my code:
<bc4j:rootAppModuleScope name="App1"
rendered="on@ctrl:page">
Now, I want to change the value of "on@ctrl:page" to "true" after user click a button so that part of the page will be displayed. But how do I assign the value to "on@ctrl:page". I tried to put the followings in my even handler:
<bc4j:setPageProperty name="on" value="true">
<bc4j:parameter name="on" />
</bc4j:setPageProperty>
But it doesn't work. Could someone pls tell me how I should do it.
Thanks a lot!
Ling

Answer 1

You should do is:
in your event handle codes,you add the list:
public static EventResult eventname(
BajaContext context,
Page page,
PageEvent event) throws Throwable
EventResult result = new EventResult(page);
result.setProperty("on","true");//or "false"
return result;
then,
change
rendered="on@ctrl:page" -> data:rendered="on@ctrl:eventResult"
also ,you should see the 5th part of 'UIX Developer's Help'