Mechanism to wait for Extjs asynchronous events

[hubefonseca]

It might be possible to register for a generic Ext event, and then be notified when such event occurs.
Then, it should be possible to make things like this:

A) ref = subscribe(extObj, 'evento')
B) extObj.click()
C) ref.waitFor()

A) Subscribe listener for an event (callback to change the flag state)
B) some code
C) pooling till true or timeout