data_onmouseover and data_onmouseout not always fired with bar graph

With C3 v0.6.7 I have noticed that `data_onmouseover `and `data_onmouseout `are not always fired when you move the cursor over a bar graph. Curiously, in previous C3 version I was using this was working correctly.

- See jsfiddle with C3 v0.6.7 : https://jsfiddle.net/xk4btuL2/2/

- Compare with jsfiddle with C3 v0.4.24 : https://jsfiddle.net/6q4y5m1k/1/

Those were tested in Chrome v69.0.3497 and FF v62.0.2 on Windows 8.1 OS

I would like to have en event handler for each bars mouseover and mouseout. What should I do?

Start by reproducing the behavior in the linked jsfiddle using C3 v0.6.7, then compare it with the C3 v0.4.24 example. Trace the bar mouseover and mouseout event entry points and verify that each bar invokes both handlers consistently in the supported browsers.

Written by the indexing model from the issue text.