Event that emits with the new current theme whenever it changes.
For this window's own consumers — the document's theme stylesheet — which need the cache to have
been updated by the time they react, so subscribing to the host separately would be a race
between two deliveries of the same change.
Event that emits with the new current theme whenever it changes.
For this window's own consumers — the document's theme stylesheet — which need the cache to have been updated by the time they react, so subscribing to the host separately would be a race between two deliveries of the same change.