But...I am looking at Phil's posting after mine, I am really glad some one in Sencha team looked into it and ran into same problem. I am going to try out Phil's suggestion and post back on this thread. I feel a lot comfortable now.
Phil, Thank you for the pointer that setting autoDestroy to false produces erroneous results in child views.
I went with your suggestions and stuck with it. The reason the button in child view does not respond to tap is that - when you press 'back' button in navigation view - not only does it pop the view , when you recreate it, Listeners need to be explicitly added as well.
Once I added the Listeners, it started to work again.
I wish this was communicated in detail when ST2.0 GA was rolled out last week. This has pretty much cost me the last several days and not to talk about the frustration.
But, Phil I Thank you for taking time to respond and
zmagyar for restarting this thread.
I am ready to move on now.