I'm completely aware of options like android:theme="@android:style/Theme.NoTitleBar" and FEATURENOTITLE to hide the title bar. But, I have an app where I need the title bar shown ONLY when the progress bar is loading. Then it disappears after the progress bar has reached the end. Is this possible?

I don't think that you can show/hide title bar after you have called setContentView() on activity, because it is done with requestWindowFeature() which should be called before setting content view. So, may be one of the approaches is reloading content view. But I'm not 100% sure. You may try to experiment.

One of the alternative approaches that you might want to use is to create your own viewgroup that can be placed on top of the screen as your own title bar or use custom title bar feature.
Check this out
my_own_titlebar_backbutton_like_on_the_iphone-t4591.html
http://stackoverflow.com/questions/8203 ... t-run-time