gtk-rs examples for gtk4

A few gtk-rs examples for gtk4. To build, just do:

> cargo build

or to enable GTK 4.x depending on the version needed by the example (check Cargo.toml [features] to see all specific GTK compile features available):

> cargo build --features [feature]
> cargo build --all-features

And then run the executables with:

./target/debug/EXAMPLE-NAME

or with cargo run (repeating the compilation features used above), example:

cargo run --all-features --bin EXAMPLE-NAME

Please be sure to have installed all the required libraries before building examples (the list is available on the gtk-rs repository).

LICENSE

The gtk-rs examples repository is licensed under the MIT license, please refer to the LICENSE and COPYRIGHT files for more information.