Fix tooltip api callback

c3.js

@@ -6863,13 +6863,13 @@
         $$.dispatchEvent('mouseover', index, mouse);
         $$.dispatchEvent('mousemove', index, mouse);
 
-        this.config.tooltip_onshow.call($$, args.data);
+        $$.config.tooltip_onshow.call($$, args.data);
     };
     c3_chart_fn.tooltip.hide = function () {
         // TODO: get target data by checking the state of focus
         this.internal.dispatchEvent('mouseout', 0);
 
-        this.config.tooltip_onhide.call(this);
+        this.internal.config.tooltip_onhide.call(this);
     };
 
     // Features:

src/api.tooltip.js

@@ -29,11 +29,11 @@ c3_chart_fn.tooltip.show = function (args) {
     $$.dispatchEvent('mouseover', index, mouse);
     $$.dispatchEvent('mousemove', index, mouse);
 
-    this.config.tooltip_onshow.call($$, args.data);
+    $$.config.tooltip_onshow.call($$, args.data);
 };
 c3_chart_fn.tooltip.hide = function () {
     // TODO: get target data by checking the state of focus
     this.internal.dispatchEvent('mouseout', 0);
 
-    this.config.tooltip_onhide.call(this);
+    this.internal.config.tooltip_onhide.call(this);
 };