https://twitter.com/simevidas/status/1304244241691029504 https://w3c.github.io/manifest/#dom-displaymodetype-fullscreen http://output.jsbin.com/sizejuw/quiet
<rdar://problem/68680815>
We're having a real problem of not being able to distinguish macOS fullscreen mode from normal a "maximised" browser window. We've tried various techniques of measuring the window width/height and comparing with window.screen values, but it yields inconsistent results for laptop and external monitor screens. Ideally, the test below (http://output.jsbin.com/sizejuw/quiet) would say "Fullscreen: Yes" when a Safari window is put in macOS fullscreen mode. That CSS Media Query could also be used from Javascript. Second best, there'd be a Javascript API in the Fullscreen API spec for this (the existing APIs only seem to concern themselves with putting specific elements into fullscreen – not the window itself).