Combine a group of elements for highlighting

[Murray]

Hello Alfred

In your Vol 2, December 16th, 2020 workshop you mentioned 

"Combined highlighting of objects seems to be impossible if triggered from board events"

I had a go at it without using board events (rather, native JS eventListeners), and making use of SVG's native <g> tag, as well as JSXGraph's in-built 'group' facility.

Here's the fiddle: https://jsfiddle.net/mbourne/7kjfyphn/

If you mouse over point D and drag it, I believe it does something like what is required. Mouse over on the other points and the lines almost work, but it's interfering with the normal highlighting. As this is a rough proof of concept, I didn't address that part.

Regards

Murray