Michał Gołębiowski-Owczarek

Thanks for the report. Is this an issue with jQuery UI or its Download Builder?

OK. jQuery UI issues should be reported at https://github.com/jquery/jquery-ui/issues, not here; let me move this issue there.

Since the issue is already in 1.12, given limited team resources it's not likely to be fixed by the UI team; see the project status at https://blog.jqueryui.com/2021/10/jquery-maintainers-update-and-transition-jquery-ui-as-part-of-overall-modernization-efforts/. PRs are welcome...

Can you provide a test case on [JS Bin](https://jsbin.com/qawicop/edit?html,css,js,output) as the issue template requested? Thanks!

Thanks for the test case! I reduced the test case to not include any external JS/CSS files: https://jsbin.com/jafisol/edit?html,css,js,output Note: to reproduce it reliably, pop-out to a preview mode: https://output.jsbin.com/jafisol. In...

The issue is reproducible in Safari 12.1 since jQuery 3.2.0. The first bad commit: 6d43dc42337089f5fb52b715981c12993f490920 (cc @markelog).

@Manuel-Suarez-Abascal Thanks for the info! I confirm it's broken in IE 11 in the same way and that the same commit, 6d43dc4, that broke Safari is also the first to...

I investigated it a little; I thought this is just a browser issue in IE & Safari but it turns out it's more complex. If you set `window.requestAnimationFrame` to `null`...

The risk here is that the proposed mechanism skips the logic used to handle classes which can bite in future changes to the library. I'm not that happy with hacks...

Thanks for the report. Can you provide a test case on [JS Bin](https://jsbin.com/qawicop/edit?html,css,js,output)? Without a test case, there's not much we can do.