Fix Declarative Services combo box alignment

Also bump the controls decorators out a bit as on Windows they are
directly next to their respective controls.

Before & After:

![image](https://cloud.githubusercontent.com/assets/114601/4392493/19631cb0-440f-11e4-83bc-ce8d01ce4b98.png)


I'm not sure how this will affect other platforms, but I'm guessing it should be OK.