- Middle-mouse drag inside a browser webview is forwarded as canvas pan
(previously eaten silently by the guest compositor).
- Horizontal-dominant wheel inside a browser webview pans the canvas
when no ancestor in the guest page can absorb horizontal scroll;
otherwise the page handles it.
- Horizontal-dominant wheel over a chat panel pans the canvas (chat has
no horizontal scroller). Vertical scroll is unchanged.
Plain vertical scroll and ctrl/meta+wheel zoom over a browser stay with
chromium's defaults.
abccodes