Mouse wheel event issue in WWTJupyterWidget

[hickst]

When scrolling over the WWTJupyterWidget in a JupyterLab notebook, the content correctly zooms in & out but the entire notebook page also scrolls.

I've created a video in Dropbox (https://www.dropbox.com/s/pncw89v3qvpc87d/pywwt-event-issue.mp4?dl=0) which shows a series of mouse wheel ratchets (forward and backward) where the astro image is correctly zooming but notice that the scroll bar is also moving and the page is scrolling for each mouse ratchet.

In other event based systems I have seen, this could be caused by the receiving widget handling the event and then "passing it through" to the parent GUI components (as opposed to killing the event because it's already been handled).