A BBC navigation bar component broke depending on the external monitor

I've searched for reasons and couldn't find much. The fact that a website can know where a browser window is located (window.screenX/window.screenY) and that clicks position can be reported in that coordinate system sounds insane for a desktop. TOR Browser seems to spoof screenX and screenY to avoid fingerprinting.

Has anyone seen good use-cases for that feature? I'm thinking about dual window applications that interacts with each other (I think I saw a demo of something like this a while ago on HN but I wasn't able to find it again), or sites where behavior depends on their location on the virtual screen.

The webkit report talks about it (https://bugs.webkit.org/show_bug.cgi?id=281430), while the article doesn't seem to, for some reason. Another HN comment with summary: https://news.ycombinator.com/item?id=42174177

Back in html 4 days we did this shenanigans all the time. I worked on very over the top sites that played with multiple windows talking to each other and moving in synchrony. I’ve tried looking for examples on archive.org (eg I know we did this a ton on flash heavy sites like design museum in London ) but alas the ones I was looking for a broken in that archive.

Maybe this[1] is the demo you were thinking of? It's what came to mind when reading this chain at least.

[1] https://x.com/wesbos/status/1727730566143803522

Not the one I was thinking one but definitely the vibe, thanks for sharing.