in src/behavior.ts [85:100]
public renderSelection(hasSelection: boolean): void {
const {
selection,
hasHighlights,
} = this.options;
selection.style("opacity", (dotPoint: LineDotPoint) => {
return getFillOpacity(
dotPoint,
dotPoint.selected,
dotPoint.highlight,
!dotPoint.highlight && hasSelection,
!dotPoint.selected && hasHighlights
);
});
}