API doc says:
Calling this method prevents all user input while the event is being processed, including while the event is propagated to the server. The UI is automatically unblocked when processing for this event is complete. Ignores request for events that do not propagate to the server.
You can download the sample workspace from here.
[Runs with Oracle JDeveloper 11g R1 PS2 + HR Schema].
How to run this sample?
1. Run test.jspx
2. Click on Search button.