Accessibility - improved experience for screen reader users, support for dynamic data and drilldown, as well as support for voice input software.
Added inactive states to series and points, allowing other series to be dimmed when the user is hovering the data or legend. To bring back the old series dimming behavior, set plotOptions.series.states.inactive.opacity to 1.
Added Verlet integration for network graphs. Generally improved network graph algorithms.
Added data labels to links in network graphs.
UPGRADE NOTESEXPANDCOLLAPSE
Changed default X axis tickWidth option. Now tick marks are not rendered by default on category axes. Set the tickWidth to 1 to bring back the old behaviour.
The new inactive state makes other items dim when hovering a series. To bring back the old series dimming behavior, set plotOptions.series.states.inactive.opacity to 1.
50 BUGFIXESEXPANDCOLLAPSE
Fixed #10009, wrong tooltip size with useHTML and varying text lengths.
Fixed #10010, series.update destroyed points and lost their event handlers.
Fixed #10031, long dataLabels for pie with useHTML: true, were generated with width less than 0.
Fixed #10052, chart printing failed with error on IE11.
Fixed #10055, exporting custom annotation did not work for other types than SVG.
Fixed #10063, proximate legend layout did not account for axis top setting.
Fixed #10081, chart with parallelCoordinates was not resizing properly after update.
Fixed #10082, points below Y axis min in polar charts were drawn incorrectly.
Fixed #10101, bubble legend was duplicated with map module.