feat(widget): add dropdown widget as pick_list replacement

The Dropdown widget is based on the PickList widget from iced.

src/theme/style/dropdown.rs

@@ -0,0 +1,28 @@
+// Copyright 2023 System76 <info@system76.com>
+// SPDX-License-Identifier: MPL-2.0
+
+use crate::widget::dropdown;
+use crate::Theme;
+use iced::{Background, Color};
+
+impl dropdown::menu::StyleSheet for Theme {
+    type Style = ();
+
+    fn appearance(&self, _style: &Self::Style) -> dropdown::menu::Appearance {
+        let cosmic = self.cosmic();
+
+        dropdown::menu::Appearance {
+            text_color: cosmic.on_bg_color().into(),
+            background: Background::Color(cosmic.background.component.base.into()),
+            border_width: 0.0,
+            border_radius: 16.0.into(),
+            border_color: Color::TRANSPARENT,
+
+            hovered_text_color: cosmic.on_bg_color().into(),
+            hovered_background: Background::Color(cosmic.primary.component.hover.into()),
+
+            selected_text_color: cosmic.accent.base.into(),
+            selected_background: Background::Color(cosmic.primary.component.hover.into()),
+        }
+    }
+}

src/theme/style/iced.rs

@@ -364,6 +364,7 @@ pub enum Container {
     Background,
     Card,
     Custom(Box<dyn Fn(&Theme) -> container::Appearance>),
+    Dropdown,
     HeaderBar,
     Primary,
     Secondary,
@@ -447,6 +448,19 @@ impl container::StyleSheet for Theme {
                 }
             }
 
+            Container::Dropdown => {
+                let theme = self.cosmic();
+
+                container::Appearance {
+                    icon_color: None,
+                    text_color: None,
+                    background: Some(iced::Background::Color(theme.primary.base.into())),
+                    border_radius: f32::from(theme.space_xxs()).into(),
+                    border_width: 1.0,
+                    border_color: theme.bg_divider().into(),
+                }
+            }
+
             Container::Tooltip => {
                 let theme = self.cosmic();
 
@@ -593,8 +607,7 @@ impl menu::StyleSheet for Theme {
             border_width: 0.0,
             border_radius: 16.0.into(),
             border_color: Color::TRANSPARENT,
-            selected_text_color: cosmic.on_bg_color().into(),
-            // TODO doesn't seem to be specified
+            selected_text_color: cosmic.accent.base.into(),
             selected_background: Background::Color(cosmic.background.component.hover.into()),
         }
     }

src/theme/style/mod.rs

@@ -6,6 +6,8 @@
 mod button;
 pub use self::button::Button;
 
+mod dropdown;
+
 pub mod iced;
 pub use self::iced::Application;
 pub use self::iced::Checkbox;