Enable the scrolling for the page if mouse pointer is on graph.

Hi,

I am working with c3.js library. I have enabled the graph zoom for graphs and zooming for graph will work only after I am clicking on graph. I have added one more condition in if condition to enable graph zoom on click:-
if (config.zoom_type === 'scroll' && !config.zoom_disableDefaultBehavior && **allowZoomForGraph**) {}
Now I want to enable the scrolling for whole page, even mouse pointer is on graph.

Start from the zoom handling condition shown in the issue, including config.zoom_type, config.zoom_disableDefaultBehavior, and allowZoomForGraph. Trace how pointer and scroll events are handled around the graph, then verify that the page scrolls while the pointer is over the graph without losing the requested graph-zoom behavior.

Written by the indexing model from the issue text.