Fixed margins on large screens

When I added the filter frame a couple of commits before, I mixed horizontal and vertical margins resulting in a displacement for larges screens in landscape mode :

![tab_before](https://f.cloud.github.com/assets/3890441/1020470/a4c37afa-0ca4-11e3-8a9d-afc86bd26d12.jpg)

Now it's fixed, and I added a custom margin for the list in order to align the list with the rest of the gui.

![tab_after](https://f.cloud.github.com/assets/3890441/1020471/c9683076-0ca4-11e3-9c82-4c1ea41d80e2.jpg)