Call for Testing for Slint 1.18

[ogoffart]

The pre-release/1.18 branch is ready for testing! 🎉

Your feedback is key to catching regressions early and polishing the final release.
Please try the highlights below with your own applications and let us know how it goes.

✨ Highlights in Slint 1.18

• Flexbox — the new FlexboxLayout element wraps its children to the next line when they don't fit.
• Spring animations — the new physics-based spring easing curve keeps its velocity when the target changes.
• Editable models — new push, remove, and insert functions on arrays and models, also available in the Model API of every language binding.
• Dynamic z-ordering — the z property can now change at runtime.
• Custom title bars — the new WindowMoveArea element lets the user move the window by dragging your own title bar.
• Experimental Vello renderer — Enable the renderer-vello feature and try it with `SLINT_BACKEND=winit-vello.
• Node.js — the Slint event loop is now integrated with the Node.js event loop on Windows, too.

Two changes to watch out for in existing projects: binding loops through two-way bindings are now compile-time errors, and the viewport-* properties of Flickable are deprecated in favor of content-*.

…and many more fixes — see the full ChangeLog.

🧪 How to test

Try the nightly build with your own projects and report anything that looks like a regression or unexpected behavior.
Per-language install instructions are on the nightly release page:

👉 https://github.com/slint-ui/slint/releases/tag/nightly

Feedback is very welcome via GitHub Issues or on our chat.
Thank you for helping us make Slint 1.18 a great release! 🙏