Summary: This issue shows up if you have a really long left nav item. When the navigator is pushed in iOS, the long nav item will be visible alongside the new nav item.
Steps to repro:
1/ Modify Examples/UIExplorer/Navigator/NavigationBarSample.js
2/ In NavigationBarRouteMapper.LeftButton, make the following change
<Text style={[styles.navBarText, styles.navBarButtonText]}>
Very Long Title {previousRoute.title}
</Text>
3/ On iOS, get the UIExplorer project up and navigate to Navigator > Navbar Example > Next (top-right nav item) > Next
You should see the overlap.
<img width="592" alt="leftnavitem_issue" src="https://cloud.githubusercontent.com/assets/691109/11086934/b5b82e26-880a-11e5-9945-13901346a5c5.png">
With these changes the overlap is gone.
Closes https://github.com/facebook/react-native/pull/4067
Reviewed By: svcscm
Differential Revision: D2641934
Pulled By: ericvicenti
fb-gh-sync-id: 962536b97f77a3b7f176423aa11dc94f24f07332
Summary: This allows for the iOS-style navigation bar on Android and vice versa in order to simplify design. It is entirely optional in that NavigationBars will continue to defauly to their platform-specific style, but you can override it with the `navigationStyles` prop:
```js
<Navigator.NavigationBar
navigationStyles={Navigator.NavigationBar.StylesIOS}
/>
```
Fixes#2995.
Closes https://github.com/facebook/react-native/pull/3028
Reviewed By: @svcscm
Differential Revision: D2527902
Pulled By: @ericvicenti
fb-gh-sync-id: c7b1bfac200b5e03fc0d9dfb8acc8b916c825595
dragonwong
Oleg Lokhvitsky
Huang Yu
Christine Abernathy
James Ide
