Hello,
We have been recently testing the a11y module and discovered a possible bug with the Firefox implementation.
When you select the legend with keyboard you can toggle the series on/off with either space or return. But in Firefox the spacebar does not work, only return. I've tried a few other things and it only seems to be this element in this browser that has the issue.
I've done multiple searches but found nothing on the issue being reported or known or having a workaround. This is repeatable on the basic JSFiddle demo http://jsfiddle.net/highcharts/LLExL/
Should I open a bug report on the github pages for this issue?
Many thanks,
Toni