The mouse pointer is supposed to be hidden after a few seconds of fullscreen video playback when it is not being moved around. This is no longer working properly.
Strangely, the pointer actually does disappear, but only when moved to the edge of the screen. I'm not sure why that happens, but it's not enough. This is a recent-ish regression. I'm pretty sure it worked last year.
Created attachment 390090 [details] Patch
Thanks for the patch. If this patch contains new public API please make sure it follows the guidelines for new WebKit2 GTK+ API. See http://trac.webkit.org/wiki/WebKitGTK/AddingNewWebKit2API
Comment on attachment 390090 [details] Patch My hero!
Comment on attachment 390090 [details] Patch Clearing flags on attachment: 390090 Committed r256113: <https://trac.webkit.org/changeset/256113>
All reviewed patches have been landed. Closing bug.
<rdar://problem/59305111>