Thanks to BKeeney Briefs, I know that in 2017r1 this:
The problem is that I used this to send the current scroll position back to my app when the viewer was scrolled. This was then used if the page’s HTML needed to be completely reloaded, it could scroll back to the same position it was at before.
Yeah, the only way now is to use TitleChanged.
If you are sending more data than the scroll position keep in mind that the Title element is limited to 4kb, so you may have to paginate larger blobs of data.