The sizes in simplelaoyout controls should not be affected by font-size.

The paddings in simplelayout controls are optimized for a 12px font-size.
If you use a bigger font for example the buttons padding change.
We can always use 12px font-size for sl-controls because there is no text inside them. 

![bildschirmfoto-2013-07-24-um-09 46 35](https://f.cloud.github.com/assets/157533/847234/c1108d46-f436-11e2-8387-c7cd4d54af1a.png)

@jone @maethu