Window/Level Quick Keys don't work immediately after scrolling using the side bar

[jenny-hm-lee]

Bug Report

Version: v3.1 from v3_stable branch and older version of master branch.

Steps to Reproduce:

1. go to https://v3-demo.ohif.org/
2. Open any series with 100+ CT images
3. Scroll through slices with your mouse scroll wheel
4. Change window/level with quick key by typing 1,2,3,4,5
5. Yes, the contrast has changed. Good.
6. Scroll through slices with the scroll bar
7. Change window/level with quick key by typing 1,2,3,4, 5
8. NO, the contrast don't change.