Properly handle index scopes overflow

For #2743, starting from #2667

Now you get this:
![screen shot 2013-11-28 at 8 53 33 pm](https://f.cloud.github.com/assets/688886/1642829/1ce57278-58a3-11e3-9102-c970d04a3b6d.png)

The only downside is this layout relies on a static, preset width for the batch actions button. For languages with a longer button translation, this happens:
![screen shot 2013-11-28 at 8 54 05 pm](https://f.cloud.github.com/assets/688886/1642834/42eb5640-58a3-11e3-9685-ca193102cfd4.png)