Added support for useHTML property to rotated data labels.
Changed the default inactive.opacity for venn diagrams to ease perception, see #10663.
Added new option pattern.patternTransform that allows SVG patternTransform functions on a pattern.
Fullscreen module added. Allows using the chart.toggleFullscreen() method.
Automatically dismiss popup content, such as tooltips, when user presses ESC key.
Changed the behavior of keyboard navigation. It no longer opens export menu automatically, but sets focus to the button.
Improvements to sonification.
Introduced the new options plotOptions.series.custom, series.custom, and series.data.custom to store additional data for custom formatters and custom event callbacks.
UPGRADE NOTESEXPANDCOLLAPSE
The Highcharts.Color constructor will not work without the new keyword. Use either new Highcharts.Color or the Highcharts.color factory.
34 BUGFIXESEXPANDCOLLAPSE
Fixed wrong x-range drag handles issue with multiple series, see #12878.
Fixed #12934, responsive rules didn’t work for drill-up button initially.
Fixed #12949, using multiple drilldown with data sorting threw an error.
Fixed tooltip position on sankey diagram links and nodes when tooltip.followPointer was false.
Fixed #12926, dumbbell marker was incorrectly colored after mouse out when series.marker.fillColor was defined.
Fixed #11917, errors and failed rendering of sankey chart if the number of nodes was too great. Fixed by reducing the nodePadding below its setting to allocate space for all nodes.