client-side cells break notebook scrolling

[jaked]

When the pointer is over the rendered output of a client-side cell, scrolling (e.g. with two-finger swipe) doesn't scroll the notebook.

[jaked]

what I've learned so far:

• ordinarily when the pointer is over a scroll container, a scroll gesture causes the container to scroll to its scroll boundary; then scrolling chains up the container chain.
• in VS Code notebooks, outputs are rendered in an iframe (a single iframe for the whole notebook), which is overlayed on the notebook; individual outputs are absolutely positioned to their correct position in the notebook.
• client-side cells have an additional iframe that points to the vitale server; this is a cross-domain link (but here's an example of a cross-domain iframe with working scroll chaining https://csreis.github.io/tests/cross-site-iframe.html)

[jaked]

I tried as best I could to reproduce the situation with a bunch of nested iframes and similar CSS, but scrolling works fine in my repro :(