Migrating From 0.2.x

This branch documents the 0.3.x API only. If you are coming from 0.2.x, the important change is conceptual: Twill is now a style-composition crate, not a component crate and not a CSS serialization layer.

What changed

• Style is the center of the public API.
• Backend adapters stay feature-gated and convert Twill values into egui, iced, and slint types.
• Legacy component demos and CSS-oriented APIs belong to the 0.2.x line.

Recommended 0.3.x path

Start with:

#![allow(unused)]
fn main() {
use twill::prelude::core::*;
}

Use the full prelude only when you need advanced arbitrary/custom-property wrappers:

#![allow(unused)]
fn main() {
use twill::prelude::{arbitrary::*, core::*};
}

Practical API updates

• Prefer Style::background_color(...) when discoverability matters; bg(...) still exists.
• Prefer data_attr(DataState::..., ...) and aria_attr(AriaAttr::..., ...) over raw strings.
• Prefer Style::at_breakpoint(...) in normal application code.
• Use at_sm / at_md / at_lg / at_xl / at_2xl if the short breakpoint builders feel too terse.
• Prefer Style::surface(), Style::card(), and Style::interactive() as reusable starting points.
• Prefer merged(...) or merge_in_place(...) for explicit style composition.

What did not change

• The short DSL remains available.
• Raw escape hatches like data_state("...") and aria_state("...") still exist.
• Backend support is still opt-in through Cargo features.

Validation checklist

• Replace broad starter imports with prelude::core::* where possible.
• Update raw data-state / aria-* selectors to typed helpers when the built-in enums cover the case.
• Re-run:

cargo clippy --workspace --all-targets --all-features -- -D warnings
cargo test --workspace --all-features
cargo check --workspace --all-features --examples