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/114601/4392485/e2f2e1ec-440e-11e4-879b-b17a0623093f.png)

I'm not sure how this will affect other platforms, but I'm guessing it should be OK.