Line-up tab bar height with file browser header

Slightly enlarging tab bar height so it seamlessly integrates with file navigation header.

![Zrzut ekranu 2013-01-30 o 01 32 44](https://f.cloud.github.com/assets/103067/109299/e7ae88ae-6a75-11e2-820f-d3f559867b69.png)