Paint UI before starting long running task

[Zbynek Vavros]

Hi,

I got a wizard and one of its steps display loading image while
processing long running task. After this task JavaScript is being called.

I've put the code into render renderHead() method of the step itself:

@Override
public void renderHead(IHeaderResponse response) {
    // process task
    String taskResult = ...
    // call JavaScript with result
    response.render(OnDomReadyHeaderItem.forScript("jsFunction(" +
taskResult + ")"));
}

When I click the NEXT button, this long running task is executed before
the step with loading image is rendered.
I guess I need to move the code somewhere else than renderHead() but where?

Thanks,
Zbynek