Replace WidgetMut methods with free functions. #1998

Job	Run time
cargo check (msrv) (wasm32)	18s
cargo check (aarch64-android)	21s
cargo clippy (windows-latest)	3m 59s
cargo clippy (macos-latest)	1m 41s
cargo check (msrv) (windows-latest)	2m 10s
cargo clippy (ubuntu-latest)	5m 38s
cargo check (msrv) (macos-latest)	30s
cargo doc	1m 26s
cargo clippy (wasm32)	3m 0s
cargo check (msrv) (ubuntu-latest)	57s
formatting	29s
Prime LFS Cache	7s
cargo test (wasm32)	24s
typos	4s
cargo test (windows-latest)	3m 46s
cargo test (macos-latest)	1m 36s
cargo test (ubuntu-latest)	4m 2s
	30m 28s

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