Bug in the legend for chart.hide() function

First, thank you for this nice library!
I think there is a bug in the legend while using this function.
**BUG**: Data in the legend is still showing as _Show state_ when you show/hide the legend manually and via Javascript at the same time.
Follow the next steps:
1. Go to c3js.org/gettingstarted.html
2. Go to **4. Use APIs** > **3. Show/Hide Data** section.
3. Click "data3" in the legend to hide it manually.
4. Click big blue "Hide" button.
5. Both data2 and data3 are hidden in the chart, but "data2" is still in _show state_ in the legend. (Note: if you move the mouse over the legend, it hides)