

How does the Twitter iPhone App animate the current tab bar indicator? - boctor
http://idevrecipes.com/2010/12/17/twitter-app-tab-bar-animation/

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kevinelliott
There has been much debate about making customizations like these that stray
from the UI guidelines. I actually like subtle customizations like these, but
some more orthodox folks feel that it's a crime.

In any case, it's nice to see someone reverse engineering some of them, as
I've always wondered how a few of them worked.

