Preverse scrollbar gap when op

[namjul]

Closes #449

Before:

After:

The header is fixed thereof ignores the padding-right on body from reserveScrollBarGap
Did not checked why the right sidebar moves.

Anyway this just adds a padding-right of scroll-bar-width.

[ariakit-bot]

Deploy preview for reakit ready!

Built with commit 718a096

https://deploy-preview-450--reakit.netlify.com

[diegohaz]

Hi @namjul! Could you please run yarn test -u to update snapshots?

[namjul]

It does not change any snapshots. The tests run successfully locally. The failed build seams to come from the gatsby build..

[diegohaz]

Your branch was several commits outdated. I guess that's why it was working locally. Updated it and it's working now! Thanks! 😊

[codecov-io]

Codecov Report

Merging #450 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff           @@
##           master    #450   +/-   ##
======================================
  Coverage    95.3%   95.3%           
======================================
  Files          94      94           
  Lines        1427    1427           
  Branches      446     446           
======================================
  Hits         1360    1360           
  Misses         67      67

Impacted Files	Coverage Δ
.../reakit/src/Dialog/__utils/usePreventBodyScroll.ts	100% <100%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 36e0d63...718a096. Read the comment docs.

[ariakit-bot]

Thanks a lot for contributing!

Based on our community guidelines, every person who has a PR of any kind merged is offered an invitation to the Reakit organization.

Should you accept, you'll get write access to the main repository and a fancy Reakit logo on your GitHub profile. You'll be able to label and close issues, create new branches etc. Make sure to read our contribution and community guidelines, which explains all of this in more detail.

If you have any questions, let me know!