Steps to reproduce the problem: 1. First you need a high resolution monitor (e.g. iMac 5K) 2. Start Safari and maximize your window 3. Go to http://threejs.org/examples/webgl_interactive_cubes.html What is the expected behavior? When you position your mouse exactly over a cube, it should be highlighted. What went wrong? On ultrad HD resolutions the application is not able to determine the correct cube. This problem only occurs when Safari exceeds a specific resolution. On smaller monitors (e.g.FullHD), everything works fine. Did this work before? No Details: I assume that Webkit must be limiting the maximum drawing buffer width/height which leads to incorrect canvas sizes. My recommendation is to change the backbuffer limit from e.g. 4k per dimension to 4k x 4k total area like Blink does (see https://bugs.chromium.org/p/chromium/issues/detail?id=445542)
rdar://problem/25511381
This problem is becoming increasingly critical as more users have high-resolution displays. Without any workarounds, interactive 3D applications like the mentioned three.js demo are unusable in combination with a large canvas.
Dup of bug 178223?
Yes. Although your mentioned bug is far newer than this post. Also consider the fix of Blink (https://bugs.chromium.org/p/chromium/issues/detail?id=445542). *** This bug has been marked as a duplicate of bug 178223 ***