Mark handled keydown events as handled

[johnjesse]

The Arrow keys are used by the browser to scroll, and DayPicker uses them to navigate months and years on the body of the DayPicker. Currently these events are not marked as handled so the browser does it's default action - which is scrolling when in a container that scrolls, and they bubble to anyone else listening higher up the tree. I've used the cancel event helper to stop that happening.

Here is a sandbox that highlights the issue https://codesandbox.io/s/1q60jqr9ml

[codecov]

Codecov Report

Merging #844 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master   #844   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          15     15           
  Lines         645    649    +4     
  Branches      141    141           
=====================================
+ Hits          645    649    +4

Impacted Files	Coverage Δ
src/DayPicker.js	100% <100%> (ø)	⬆️

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[codecov]

Codecov Report

Merging #844 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master   #844   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          15     15           
  Lines         645    649    +4     
  Branches      141    141           
=====================================
+ Hits          645    649    +4

Impacted Files	Coverage Δ
src/DayPicker.js	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 39ad48e...e0c3034. Read the comment docs.

[codecov]

Codecov Report

Merging #844 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master   #844   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          15     15           
  Lines         653    657    +4     
  Branches      145    145           
=====================================
+ Hits          653    657    +4

Impacted Files	Coverage Δ
src/DayPicker.js	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 072e305...cc46260. Read the comment docs.

[gpbl]

Hey thank you – sorry for the late merge.