Draft first-class `Theme` support

RFC: https://github.com/iced-rs/rfcs/pull/6

9 files changed, 165 insertions, 88 deletions

diff --git a/src/application.rs b/src/application.rs
index 11735b93..f05d2c4b 100644
--- a/src/application.rs
+++ b/src/application.rs
@@ -57,7 +57,7 @@ use crate::{Color, Command, Element, Executor, Settings, Subscription};
 /// says "Hello, world!":
 ///
 /// ```no_run
-/// use iced::{executor, Application, Command, Element, Settings, Text};
+/// use iced::{executor, Application, Command, Element, Settings, Text, Theme};
 ///
 /// pub fn main() -> iced::Result {
 ///     Hello::run(Settings::default())
@@ -67,8 +67,9 @@ use crate::{Color, Command, Element, Executor, Settings, Subscription};
 ///
 /// impl Application for Hello {
 ///     type Executor = executor::Default;
-///     type Message = ();
 ///     type Flags = ();
+///     type Message = ();
+///     type Theme = Theme;
 ///
 ///     fn new(_flags: ()) -> (Hello, Command<Self::Message>) {
 ///         (Hello, Command::none())
@@ -99,6 +100,9 @@ pub trait Application: Sized {
     /// The type of __messages__ your [`Application`] will produce.
     type Message: std::fmt::Debug + Send;
 
+    /// The theme of your [`Application`].
+    type Theme: Default;
+
     /// The data needed to initialize your [`Application`].
     type Flags;
 
@@ -129,6 +133,16 @@ pub trait Application: Sized {
     /// Any [`Command`] returned will be executed immediately in the background.
     fn update(&mut self, message: Self::Message) -> Command<Self::Message>;
 
+    /// Returns the widgets to display in the [`Application`].
+    ///
+    /// These widgets can produce __messages__ based on user interaction.
+    fn view(&mut self) -> Element<'_, Self::Message, Self::Theme>;
+
+    /// Returns the current [`Theme`] of the [`Application`].
+    fn theme(&self) -> Self::Theme {
+        Self::Theme::default()
+    }
+
     /// Returns the event [`Subscription`] for the current state of the
     /// application.
     ///
@@ -141,11 +155,6 @@ pub trait Application: Sized {
         Subscription::none()
     }
 
-    /// Returns the widgets to display in the [`Application`].
-    ///
-    /// These widgets can produce __messages__ based on user interaction.
-    fn view(&mut self) -> Element<'_, Self::Message>;
-
     /// Returns the current [`Application`] mode.
     ///
     /// The runtime will automatically transition your application if a new mode
@@ -213,7 +222,7 @@ pub trait Application: Sized {
         Ok(crate::runtime::application::run::<
             Instance<Self>,
             Self::Executor,
-            crate::renderer::window::Compositor,
+            crate::renderer::window::Compositor<Self::Theme>,
         >(settings.into(), renderer_settings)?)
     }
 }
@@ -224,14 +233,14 @@ impl<A> iced_winit::Program for Instance<A>
 where
     A: Application,
 {
-    type Renderer = crate::renderer::Renderer;
+    type Renderer = crate::renderer::Renderer<A::Theme>;
     type Message = A::Message;
 
     fn update(&mut self, message: Self::Message) -> Command<Self::Message> {
         self.0.update(message)
     }
 
-    fn view(&mut self) -> Element<'_, Self::Message> {
+    fn view(&mut self) -> Element<'_, Self::Message, A::Theme> {
         self.0.view()
     }
 }
@@ -252,6 +261,10 @@ where
         self.0.title()
     }
 
+    fn theme(&self) -> A::Theme {
+        self.0.theme()
+    }
+
     fn mode(&self) -> iced_winit::Mode {
         match self.0.mode() {
             window::Mode::Windowed => iced_winit::Mode::Windowed,
diff --git a/src/element.rs b/src/element.rs
index 8bad18c1..439a4508 100644
--- a/src/element.rs
+++ b/src/element.rs
@@ -1,5 +1,5 @@
 /// A generic widget.
 ///
 /// This is an alias of an `iced_native` element with a default `Renderer`.
-pub type Element<'a, Message> =
-    crate::runtime::Element<'a, Message, crate::renderer::Renderer>;
+pub type Element<'a, Message, Theme = iced_native::Theme> =
+    crate::runtime::Element<'a, Message, crate::Renderer<Theme>>;
diff --git a/src/lib.rs b/src/lib.rs
index 298beae3..df40ad3e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -211,6 +211,8 @@ use iced_wgpu as renderer;
 #[cfg(feature = "glow")]
 use iced_glow as renderer;
 
+pub use iced_native::theme;
+
 #[doc(no_inline)]
 pub use widget::*;
 
@@ -222,6 +224,7 @@ pub use renderer::Renderer;
 pub use result::Result;
 pub use sandbox::Sandbox;
 pub use settings::Settings;
+pub use theme::Theme;
 
 pub use runtime::alignment;
 pub use runtime::futures;
diff --git a/src/pure.rs b/src/pure.rs
index 7785a104..b2b3ade7 100644
--- a/src/pure.rs
+++ b/src/pure.rs
@@ -108,5 +108,5 @@ pub use iced_pure::Widget;
 pub use iced_pure::{Pure, State};
 
 /// A generic, pure [`Widget`].
-pub type Element<'a, Message> =
-    iced_pure::Element<'a, Message, crate::Renderer>;
+pub type Element<'a, Message, Theme = crate::Theme> =
+    iced_pure::Element<'a, Message, crate::Renderer<Theme>>;
diff --git a/src/pure/application.rs b/src/pure/application.rs
index 5f400bea..77f68c9e 100644
--- a/src/pure/application.rs
+++ b/src/pure/application.rs
@@ -21,6 +21,9 @@ pub trait Application: Sized {
     /// The type of __messages__ your [`Application`] will produce.
     type Message: std::fmt::Debug + Send;
 
+    /// The theme of your [`Application`].
+    type Theme: Default;
+
     /// The data needed to initialize your [`Application`].
     type Flags;
 
@@ -51,6 +54,16 @@ pub trait Application: Sized {
     /// Any [`Command`] returned will be executed immediately in the background.
     fn update(&mut self, message: Self::Message) -> Command<Self::Message>;
 
+    /// Returns the widgets to display in the [`Application`].
+    ///
+    /// These widgets can produce __messages__ based on user interaction.
+    fn view(&self) -> pure::Element<'_, Self::Message, Self::Theme>;
+
+    /// Returns the current [`Theme`] of the [`Application`].
+    fn theme(&self) -> Self::Theme {
+        Self::Theme::default()
+    }
+
     /// Returns the event [`Subscription`] for the current state of the
     /// application.
     ///
@@ -63,11 +76,6 @@ pub trait Application: Sized {
         Subscription::none()
     }
 
-    /// Returns the widgets to display in the [`Application`].
-    ///
-    /// These widgets can produce __messages__ based on user interaction.
-    fn view(&self) -> pure::Element<'_, Self::Message>;
-
     /// Returns the current [`Application`] mode.
     ///
     /// The runtime will automatically transition your application if a new mode
@@ -137,6 +145,7 @@ where
     type Executor = A::Executor;
     type Message = A::Message;
     type Flags = A::Flags;
+    type Theme = A::Theme;
 
     fn new(flags: Self::Flags) -> (Self, Command<Self::Message>) {
         let (application, command) = A::new(flags);
@@ -162,12 +171,16 @@ where
         A::subscription(&self.application)
     }
 
-    fn view(&mut self) -> crate::Element<'_, Self::Message> {
+    fn view(&mut self) -> crate::Element<'_, Self::Message, Self::Theme> {
         let content = A::view(&self.application);
 
         Pure::new(&mut self.state, content).into()
     }
 
+    fn theme(&self) -> Self::Theme {
+        A::theme(&self.application)
+    }
+
     fn mode(&self) -> window::Mode {
         A::mode(&self.application)
     }
diff --git a/src/pure/sandbox.rs b/src/pure/sandbox.rs
index fbd1d7a8..207a32bd 100644
--- a/src/pure/sandbox.rs
+++ b/src/pure/sandbox.rs
@@ -1,5 +1,5 @@
 use crate::pure;
-use crate::{Color, Command, Error, Settings, Subscription};
+use crate::{Color, Command, Error, Settings, Subscription, Theme};
 
 /// A pure version of [`Sandbox`].
 ///
@@ -34,6 +34,16 @@ pub trait Sandbox {
     /// These widgets can produce __messages__ based on user interaction.
     fn view(&self) -> pure::Element<'_, Self::Message>;
 
+    /// Returns the current [`Theme`] of the [`Sandbox`].
+    ///
+    /// If you want to use your own custom theme type, you will have to use an
+    /// [`Application`].
+    ///
+    /// By default, it returns [`Theme::default`].
+    fn theme(&self) -> Theme {
+        Theme::default()
+    }
+
     /// Returns the background color of the [`Sandbox`].
     ///
     /// By default, it returns [`Color::WHITE`].
@@ -82,6 +92,7 @@ where
     type Executor = iced_futures::backend::null::Executor;
     type Flags = ();
     type Message = T::Message;
+    type Theme = Theme;
 
     fn new(_flags: ()) -> (Self, Command<T::Message>) {
         (T::new(), Command::none())
@@ -97,14 +108,18 @@ where
         Command::none()
     }
 
-    fn subscription(&self) -> Subscription<T::Message> {
-        Subscription::none()
-    }
-
     fn view(&self) -> pure::Element<'_, T::Message> {
         T::view(self)
     }
 
+    fn theme(&self) -> Self::Theme {
+        T::theme(self)
+    }
+
+    fn subscription(&self) -> Subscription<T::Message> {
+        Subscription::none()
+    }
+
     fn background_color(&self) -> Color {
         T::background_color(self)
     }
diff --git a/src/pure/widget.rs b/src/pure/widget.rs
index c84edde3..1c0a32a6 100644
--- a/src/pure/widget.rs
+++ b/src/pure/widget.rs
@@ -1,23 +1,24 @@
 //! Pure versions of the widgets.
 
 /// A container that distributes its contents vertically.
-pub type Column<'a, Message> =
-    iced_pure::widget::Column<'a, Message, crate::Renderer>;
+pub type Column<'a, Message, Theme = crate::Theme> =
+    iced_pure::widget::Column<'a, Message, crate::Renderer<Theme>>;
 
 /// A container that distributes its contents horizontally.
-pub type Row<'a, Message> =
-    iced_pure::widget::Row<'a, Message, crate::Renderer>;
+pub type Row<'a, Message, Theme = crate::Theme> =
+    iced_pure::widget::Row<'a, Message, crate::Renderer<Theme>>;
 
 /// A paragraph of text.
-pub type Text = iced_pure::widget::Text<crate::Renderer>;
+pub type Text<Theme = crate::Theme> =
+    iced_pure::widget::Text<crate::Renderer<Theme>>;
 
 pub mod button {
     //! Allow your users to perform actions by pressing a button.
     pub use iced_pure::widget::button::{Style, StyleSheet};
 
     /// A widget that produces a message when clicked.
-    pub type Button<'a, Message> =
-        iced_pure::widget::Button<'a, Message, crate::Renderer>;
+    pub type Button<'a, Message, Theme = crate::Theme> =
+        iced_pure::widget::Button<'a, Message, crate::Renderer<Theme>>;
 }
 
 pub mod checkbox {
@@ -25,8 +26,8 @@ pub mod checkbox {
     pub use iced_pure::widget::checkbox::{Style, StyleSheet};
 
     /// A box that can be checked.
-    pub type Checkbox<'a, Message> =
-        iced_native::widget::Checkbox<'a, Message, crate::Renderer>;
+    pub type Checkbox<'a, Message, Theme> =
+        iced_native::widget::Checkbox<'a, Message, crate::Renderer<Theme>>;
 }
 
 pub mod container {
@@ -34,8 +35,8 @@ pub mod container {
     pub use iced_pure::widget::container::{Style, StyleSheet};
 
     /// An element decorating some content.
-    pub type Container<'a, Message> =
-        iced_pure::widget::Container<'a, Message, crate::Renderer>;
+    pub type Container<'a, Message, Theme = crate::Theme> =
+        iced_pure::widget::Container<'a, Message, crate::Renderer<Theme>>;
 }
 
 pub mod pane_grid {
@@ -57,16 +58,24 @@ pub mod pane_grid {
     /// to completely fill the space available.
     ///
     /// [![Pane grid - Iced](https://thumbs.gfycat.com/MixedFlatJellyfish-small.gif)](https://gfycat.com/mixedflatjellyfish)
-    pub type PaneGrid<'a, Message> =
-        iced_pure::widget::PaneGrid<'a, Message, crate::Renderer>;
+    pub type PaneGrid<'a, Message, Theme> =
+        iced_pure::widget::PaneGrid<'a, Message, crate::Renderer<Theme>>;
 
     /// The content of a [`Pane`].
-    pub type Content<'a, Message> =
-        iced_pure::widget::pane_grid::Content<'a, Message, crate::Renderer>;
+    pub type Content<'a, Message, Theme> =
+        iced_pure::widget::pane_grid::Content<
+            'a,
+            Message,
+            crate::Renderer<Theme>,
+        >;
 
     /// The title bar of a [`Pane`].
-    pub type TitleBar<'a, Message> =
-        iced_pure::widget::pane_grid::TitleBar<'a, Message, crate::Renderer>;
+    pub type TitleBar<'a, Message, Theme> =
+        iced_pure::widget::pane_grid::TitleBar<
+            'a,
+            Message,
+            crate::Renderer<Theme>,
+        >;
 }
 
 pub mod pick_list {
@@ -75,8 +84,8 @@ pub mod pick_list {
     pub use iced_pure::widget::pick_list::{Style, StyleSheet};
 
     /// A widget allowing the selection of a single value from a list of options.
-    pub type PickList<'a, T, Message> =
-        iced_pure::widget::PickList<'a, T, Message, crate::Renderer>;
+    pub type PickList<'a, T, Message, Theme> =
+        iced_pure::widget::PickList<'a, T, Message, crate::Renderer<Theme>>;
 }
 
 pub mod radio {
@@ -84,8 +93,8 @@ pub mod radio {
     pub use iced_pure::widget::radio::{Style, StyleSheet};
 
     /// A circular button representing a choice.
-    pub type Radio<'a, Message> =
-        iced_pure::widget::Radio<'a, Message, crate::Renderer>;
+    pub type Radio<'a, Message, Theme> =
+        iced_pure::widget::Radio<'a, Message, crate::Renderer<Theme>>;
 }
 
 pub mod scrollable {
@@ -94,8 +103,8 @@ pub mod scrollable {
 
     /// A widget that can vertically display an infinite amount of content
     /// with a scrollbar.
-    pub type Scrollable<'a, Message> =
-        iced_pure::widget::Scrollable<'a, Message, crate::Renderer>;
+    pub type Scrollable<'a, Message, Theme> =
+        iced_pure::widget::Scrollable<'a, Message, crate::Renderer<Theme>>;
 }
 
 pub mod toggler {
@@ -103,8 +112,8 @@ pub mod toggler {
     pub use iced_pure::widget::toggler::{Style, StyleSheet};
 
     /// A toggler widget.
-    pub type Toggler<'a, Message> =
-        iced_pure::widget::Toggler<'a, Message, crate::Renderer>;
+    pub type Toggler<'a, Message, Theme> =
+        iced_pure::widget::Toggler<'a, Message, crate::Renderer<Theme>>;
 }
 
 pub mod text_input {
@@ -114,8 +123,8 @@ pub mod text_input {
     pub use iced_pure::widget::text_input::{Style, StyleSheet};
 
     /// A field that can be filled with text.
-    pub type TextInput<'a, Message> =
-        iced_pure::widget::TextInput<'a, Message, Renderer>;
+    pub type TextInput<'a, Message, Theme> =
+        iced_pure::widget::TextInput<'a, Message, Renderer<Theme>>;
 }
 
 pub mod tooltip {
@@ -123,8 +132,8 @@ pub mod tooltip {
     pub use iced_pure::widget::tooltip::Position;
 
     /// A widget allowing the selection of a single value from a list of options.
-    pub type Tooltip<'a, Message> =
-        iced_pure::widget::Tooltip<'a, Message, crate::Renderer>;
+    pub type Tooltip<'a, Message, Theme> =
+        iced_pure::widget::Tooltip<'a, Message, crate::Renderer<Theme>>;
 }
 
 pub use iced_pure::widget::progress_bar;
diff --git a/src/sandbox.rs b/src/sandbox.rs
index e7e97920..16819569 100644
--- a/src/sandbox.rs
+++ b/src/sandbox.rs
@@ -1,5 +1,5 @@
 use crate::{
-    Application, Color, Command, Element, Error, Settings, Subscription,
+    Application, Color, Command, Element, Error, Settings, Subscription, Theme,
 };
 
 /// A sandboxed [`Application`].
@@ -111,6 +111,16 @@ pub trait Sandbox {
     /// These widgets can produce __messages__ based on user interaction.
     fn view(&mut self) -> Element<'_, Self::Message>;
 
+    /// Returns the current [`Theme`] of the [`Sandbox`].
+    ///
+    /// If you want to use your own custom theme type, you will have to use an
+    /// [`Application`].
+    ///
+    /// By default, it returns [`Theme::default`].
+    fn theme(&self) -> Theme {
+        Theme::default()
+    }
+
     /// Returns the background color of the [`Sandbox`].
     ///
     /// By default, it returns [`Color::WHITE`].
@@ -159,6 +169,7 @@ where
     type Executor = iced_futures::backend::null::Executor;
     type Flags = ();
     type Message = T::Message;
+    type Theme = Theme;
 
     fn new(_flags: ()) -> (Self, Command<T::Message>) {
         (T::new(), Command::none())
@@ -174,14 +185,18 @@ where
         Command::none()
     }
 
-    fn subscription(&self) -> Subscription<T::Message> {
-        Subscription::none()
-    }
-
     fn view(&mut self) -> Element<'_, T::Message> {
         T::view(self)
     }
 
+    fn theme(&self) -> Self::Theme {
+        T::theme(self)
+    }
+
+    fn subscription(&self) -> Subscription<T::Message> {
+        Subscription::none()
+    }
+
     fn background_color(&self) -> Color {
         T::background_color(self)
     }
diff --git a/src/widget.rs b/src/widget.rs
index 5e2b63fc..e40ed108 100644
--- a/src/widget.rs
+++ b/src/widget.rs
@@ -15,15 +15,16 @@
 //! [`TextInput`] has some [`text_input::State`].
 
 /// A container that distributes its contents vertically.
-pub type Column<'a, Message> =
-    iced_native::widget::Column<'a, Message, crate::Renderer>;
+pub type Column<'a, Message, Theme = crate::Theme> =
+    iced_native::widget::Column<'a, Message, crate::Renderer<Theme>>;
 
 /// A container that distributes its contents horizontally.
-pub type Row<'a, Message> =
-    iced_native::widget::Row<'a, Message, crate::Renderer>;
+pub type Row<'a, Message, Theme = crate::Theme> =
+    iced_native::widget::Row<'a, Message, crate::Renderer<Theme>>;
 
 /// A paragraph of text.
-pub type Text = iced_native::widget::Text<crate::Renderer>;
+pub type Text<Theme = crate::Theme> =
+    iced_native::widget::Text<crate::Renderer<Theme>>;
 
 pub mod button {
     //! Allow your users to perform actions by pressing a button.
@@ -32,8 +33,8 @@ pub mod button {
     pub use iced_native::widget::button::{State, Style, StyleSheet};
 
     /// A widget that produces a message when clicked.
-    pub type Button<'a, Message> =
-        iced_native::widget::Button<'a, Message, crate::Renderer>;
+    pub type Button<'a, Message, Theme = crate::Theme> =
+        iced_native::widget::Button<'a, Message, crate::Renderer<Theme>>;
 }
 
 pub mod checkbox {
@@ -41,8 +42,8 @@ pub mod checkbox {
     pub use iced_native::widget::checkbox::{Style, StyleSheet};
 
     /// A box that can be checked.
-    pub type Checkbox<'a, Message> =
-        iced_native::widget::Checkbox<'a, Message, crate::Renderer>;
+    pub type Checkbox<'a, Message, Theme> =
+        iced_native::widget::Checkbox<'a, Message, crate::Renderer<Theme>>;
 }
 
 pub mod container {
@@ -50,8 +51,8 @@ pub mod container {
     pub use iced_native::widget::container::{Style, StyleSheet};
 
     /// An element decorating some content.
-    pub type Container<'a, Message> =
-        iced_native::widget::Container<'a, Message, crate::Renderer>;
+    pub type Container<'a, Message, Theme = crate::Theme> =
+        iced_native::widget::Container<'a, Message, crate::Renderer<Theme>>;
 }
 
 pub mod pane_grid {
@@ -73,16 +74,24 @@ pub mod pane_grid {
     /// to completely fill the space available.
     ///
     /// [![Pane grid - Iced](https://thumbs.gfycat.com/MixedFlatJellyfish-small.gif)](https://gfycat.com/mixedflatjellyfish)
-    pub type PaneGrid<'a, Message> =
-        iced_native::widget::PaneGrid<'a, Message, crate::Renderer>;
+    pub type PaneGrid<'a, Message, Theme> =
+        iced_native::widget::PaneGrid<'a, Message, crate::Renderer<Theme>>;
 
     /// The content of a [`Pane`].
-    pub type Content<'a, Message> =
-        iced_native::widget::pane_grid::Content<'a, Message, crate::Renderer>;
+    pub type Content<'a, Message, Theme> =
+        iced_native::widget::pane_grid::Content<
+            'a,
+            Message,
+            crate::Renderer<Theme>,
+        >;
 
     /// The title bar of a [`Pane`].
-    pub type TitleBar<'a, Message> =
-        iced_native::widget::pane_grid::TitleBar<'a, Message, crate::Renderer>;
+    pub type TitleBar<'a, Message, Theme> =
+        iced_native::widget::pane_grid::TitleBar<
+            'a,
+            Message,
+            crate::Renderer<Theme>,
+        >;
 }
 
 pub mod pick_list {
@@ -91,8 +100,8 @@ pub mod pick_list {
     pub use iced_native::widget::pick_list::{State, Style, StyleSheet};
 
     /// A widget allowing the selection of a single value from a list of options.
-    pub type PickList<'a, T, Message> =
-        iced_native::widget::PickList<'a, T, Message, crate::Renderer>;
+    pub type PickList<'a, T, Message, Theme> =
+        iced_native::widget::PickList<'a, T, Message, crate::Renderer<Theme>>;
 }
 
 pub mod radio {
@@ -100,8 +109,8 @@ pub mod radio {
     pub use iced_native::widget::radio::{Style, StyleSheet};
 
     /// A circular button representing a choice.
-    pub type Radio<'a, Message> =
-        iced_native::widget::Radio<'a, Message, crate::Renderer>;
+    pub type Radio<'a, Message, Theme> =
+        iced_native::widget::Radio<'a, Message, crate::Renderer<Theme>>;
 }
 
 pub mod scrollable {
@@ -112,8 +121,8 @@ pub mod scrollable {
 
     /// A widget that can vertically display an infinite amount of content
     /// with a scrollbar.
-    pub type Scrollable<'a, Message> =
-        iced_native::widget::Scrollable<'a, Message, crate::Renderer>;
+    pub type Scrollable<'a, Message, Theme> =
+        iced_native::widget::Scrollable<'a, Message, crate::Renderer<Theme>>;
 }
 
 pub mod toggler {
@@ -121,8 +130,8 @@ pub mod toggler {
     pub use iced_native::widget::toggler::{Style, StyleSheet};
 
     /// A toggler widget.
-    pub type Toggler<'a, Message> =
-        iced_native::widget::Toggler<'a, Message, crate::Renderer>;
+    pub type Toggler<'a, Message, Theme> =
+        iced_native::widget::Toggler<'a, Message, crate::Renderer<Theme>>;
 }
 
 pub mod text_input {
@@ -134,8 +143,8 @@ pub mod text_input {
     pub use iced_native::widget::text_input::{State, Style, StyleSheet};
 
     /// A field that can be filled with text.
-    pub type TextInput<'a, Message> =
-        iced_native::widget::TextInput<'a, Message, Renderer>;
+    pub type TextInput<'a, Message, Theme> =
+        iced_native::widget::TextInput<'a, Message, Renderer<Theme>>;
 }
 
 pub mod tooltip {
@@ -143,8 +152,8 @@ pub mod tooltip {
     pub use iced_native::widget::tooltip::Position;
 
     /// A widget allowing the selection of a single value from a list of options.
-    pub type Tooltip<'a, Message> =
-        iced_native::widget::Tooltip<'a, Message, crate::Renderer>;
+    pub type Tooltip<'a, Message, Theme> =
+        iced_native::widget::Tooltip<'a, Message, crate::Renderer<Theme>>;
 }
 
 pub use iced_native::widget::progress_bar;