Bug 270898

Created attachment 470332 [details] Screenshot of reproduction SUMMARY: Using the old WebView class, elements with 3D transforms do not repaint when their size changes programmatically. STEPS TO REPRODUCE: 1. Create an app that uses an WebView (the pre-WKWebView one) 2. Have code like: <div id="elm" style="transform: rotateY(0deg); height: 100px; width: 100px; background-color:#ccc"></div> <script> window.setTimeout(function() { elm.style.height = "10px"; }, 1000); </script> EXPECTED RESULTS: The height of the div should change from 100px to 10px after one second. ACTUAL RESULTS: It does not change, the div continues to look like it is 100px. (If you do certain things that trigger a repaint though (like click in the webview), you will eventually see it.) FILES: I have attached a screenshot comparing WebView(Legacy) and WKWebView, along with an Xcode project that reproduces the problem. NOTES: - This is a *regression* in macOS 14.4. - It does not occur in macOS 14.3. - It does not occur with WKWebViews. - It does not occur if you remove the 'transform: rotateY(0deg)' style. HARM: This affects all users of Tumult Hype: http://tumult.com/hype/. Resizing elements is a critical function of the application!