Resze QuickOpen results if the window size is changed, and add scroll bars

These changes add a scroll-bar to the results of QuickOpen when there are more results that can fit in the screen.
It also moves the results horizontally with the QuickOpen input area.

This addresses issues #1156 and #1157

Result :
![15a2214](https://f.cloud.github.com/assets/2771653/1814639/cdd6258c-6efb-11e3-93d7-00f1d9bbf928.png)