gh-1583 added config.interaction.brighten option to disable brightening of

selected path elements

src/config.js

@@ -18,6 +18,7 @@ c3_chart_internal_fn.getDefaultConfig = function () {
         zoom_onzoomend: function () {},
         zoom_x_min: undefined,
         zoom_x_max: undefined,
+        interaction_brighten: true,
         interaction_enabled: true,
         onmouseover: function () {},
         onmouseout: function () {},

src/selection.js

@@ -30,14 +30,18 @@ c3_chart_internal_fn.togglePoint = function (selected, target, d, i) {
 c3_chart_internal_fn.selectPath = function (target, d) {
     var $$ = this;
     $$.config.data_onselected.call($$, d, target.node());
+    if ($$.config.interaction_brighten) {
         target.transition().duration(100)
             .style("fill", function () { return $$.d3.rgb($$.color(d)).brighter(0.75); });
+    }
 };
 c3_chart_internal_fn.unselectPath = function (target, d) {
     var $$ = this;
     $$.config.data_onunselected.call($$, d, target.node());
+    if ($$.config.interaction_brighten) {
         target.transition().duration(100)
             .style("fill", function () { return $$.color(d); });
+    }
 };
 c3_chart_internal_fn.togglePath = function (selected, target, d, i) {
     selected ? this.selectPath(target, d, i) : this.unselectPath(target, d, i);