Zoom/scroll events not firing in safari

[abought]

The shift+scroll to zoom feature does not work correctly in Safari.

This has been traced to a safari bug. Adding a background element (or adjusting how the SVG panel area is handled) may help resolve this, but it will require careful regression testing because each browser interprets mouse events in the SVG spec a little differently.

https://stackoverflow.com/questions/40887193/d3-js-zoom-is-not-working-with-mousewheel-in-safari