[Aziks0]

This PR adds the option to add a shadow to the pick_list widget.

Code sample for the image.

This is just the pick_list example with the added shadow:

use iced::widget::{column, pick_list, scrollable, space};
use iced::{Center, Color, Fill, Shadow, Vector, Widget};

pub fn main() -> iced::Result {
    iced::run(Example::update, Example::view)
}

#[derive(Default)]
struct Example {
    selected_language: Option<Language>,
}

#[derive(Debug, Clone, Copy)]
enum Message {
    LanguageSelected(Language),
}

impl Example {
    fn update(&mut self, message: Message) {
        match message {
            Message::LanguageSelected(language) => {
                self.selected_language = Some(language);
            }
        }
    }

    fn view(&self) -> impl Widget<Message> {
        let languages = pick_list(self.selected_language, Language::ALL, Language::to_string)
            .on_select(Message::LanguageSelected)
            .placeholder("Choose a language...")
            .style(|theme, status| pick_list::Style {
                shadow: Shadow {
                    color: Color::BLACK.scale_alpha(0.2),
                    offset: Vector::new(2., 2.),
                    blur_radius: 1.,
                },
                ..pick_list::default(theme, status)
            });

        let content = column![
            space().height(600),
            "Which is your favorite language?",
            languages,
            space().height(600),
        ]
        .width(Fill)
        .align_x(Center)
        .spacing(10);

        scrollable(content)
    }
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub enum Language {
    #[default]
    Rust,
    Elm,
    Ruby,
    Haskell,
    C,
    Javascript,
    Other,
}

impl Language {
    const ALL: &[Language] = &[
        Language::C,
        Language::Elm,
        Language::Ruby,
        Language::Haskell,
        Language::Rust,
        Language::Javascript,
        Language::Other,
    ];
}

impl std::fmt::Display for Language {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(
            f,
            "{}",
            match self {
                Language::Rust => "Rust",
                Language::Elm => "Elm",
                Language::Ruby => "Ruby",
                Language::Haskell => "Haskell",
                Language::C => "C",
                Language::Javascript => "Javascript",
                Language::Other => "Some other language",
            }
        )
    }
}