Merge pull request #2326 from iced-rs/closure-styles

Use closures for widget styling

22 files changed, 358 insertions, 367 deletions

diff --git a/widget/src/button.rs b/widget/src/button.rs
index e265aa1f..5790f811 100644
--- a/widget/src/button.rs
+++ b/widget/src/button.rs
@@ -56,7 +56,7 @@ where
     height: Length,
     padding: Padding,
     clip: bool,
-    style: Style<Theme>,
+    style: Style<'a, Theme>,
 }
 
 impl<'a, Message, Theme, Renderer> Button<'a, Message, Theme, Renderer>
@@ -68,7 +68,7 @@ where
         content: impl Into<Element<'a, Message, Theme, Renderer>>,
     ) -> Self
     where
-        Theme: DefaultStyle,
+        Theme: DefaultStyle + 'a,
     {
         let content = content.into();
         let size = content.as_widget().size_hint();
@@ -80,7 +80,7 @@ where
             height: size.height.fluid(),
             padding: DEFAULT_PADDING,
             clip: false,
-            style: Theme::default_style(),
+            style: Box::new(Theme::default_style),
         }
     }
 
@@ -120,8 +120,11 @@ where
     }
 
     /// Sets the style variant of this [`Button`].
-    pub fn style(mut self, style: fn(&Theme, Status) -> Appearance) -> Self {
-        self.style = style;
+    pub fn style(
+        mut self,
+        style: impl Fn(&Theme, Status) -> Appearance + 'a,
+    ) -> Self {
+        self.style = Box::new(style);
         self
     }
 
@@ -439,29 +442,29 @@ impl std::default::Default for Appearance {
 }
 
 /// The style of a [`Button`].
-pub type Style<Theme> = fn(&Theme, Status) -> Appearance;
+pub type Style<'a, Theme> = Box<dyn Fn(&Theme, Status) -> Appearance + 'a>;
 
 /// The default style of a [`Button`].
 pub trait DefaultStyle {
     /// Returns the default style of a [`Button`].
-    fn default_style() -> Style<Self>;
+    fn default_style(&self, status: Status) -> Appearance;
 }
 
 impl DefaultStyle for Theme {
-    fn default_style() -> Style<Self> {
-        primary
+    fn default_style(&self, status: Status) -> Appearance {
+        primary(self, status)
     }
 }
 
 impl DefaultStyle for Appearance {
-    fn default_style() -> Style<Self> {
-        |appearance, _status| *appearance
+    fn default_style(&self, _status: Status) -> Appearance {
+        *self
     }
 }
 
 impl DefaultStyle for Color {
-    fn default_style() -> Style<Self> {
-        |color, _status| Appearance::default().with_background(*color)
+    fn default_style(&self, _status: Status) -> Appearance {
+        Appearance::default().with_background(*self)
     }
 }
 
diff --git a/widget/src/checkbox.rs b/widget/src/checkbox.rs
index f0c7357b..15fb8f58 100644
--- a/widget/src/checkbox.rs
+++ b/widget/src/checkbox.rs
@@ -51,7 +51,7 @@ pub struct Checkbox<
     text_shaping: text::Shaping,
     font: Option<Renderer::Font>,
     icon: Icon<Renderer::Font>,
-    style: Style<Theme>,
+    style: Style<'a, Theme>,
 }
 
 impl<'a, Message, Theme, Renderer> Checkbox<'a, Message, Theme, Renderer>
@@ -71,7 +71,7 @@ where
     ///   * a boolean describing whether the [`Checkbox`] is checked or not
     pub fn new(label: impl Into<String>, is_checked: bool) -> Self
     where
-        Theme: DefaultStyle,
+        Theme: DefaultStyle + 'a,
     {
         Checkbox {
             is_checked,
@@ -91,7 +91,7 @@ where
                 line_height: text::LineHeight::default(),
                 shaping: text::Shaping::Basic,
             },
-            style: Theme::default_style(),
+            style: Box::new(Theme::default_style),
         }
     }
 
@@ -174,8 +174,11 @@ where
     }
 
     /// Sets the style of the [`Checkbox`].
-    pub fn style(mut self, style: fn(&Theme, Status) -> Appearance) -> Self {
-        self.style = style;
+    pub fn style(
+        mut self,
+        style: impl Fn(&Theme, Status) -> Appearance + 'a,
+    ) -> Self {
+        self.style = Box::new(style);
         self
     }
 }
@@ -424,23 +427,23 @@ pub struct Appearance {
 }
 
 /// The style of a [`Checkbox`].
-pub type Style<Theme> = fn(&Theme, Status) -> Appearance;
+pub type Style<'a, Theme> = Box<dyn Fn(&Theme, Status) -> Appearance + 'a>;
 
 /// The default style of a [`Checkbox`].
 pub trait DefaultStyle {
     /// Returns the default style of a [`Checkbox`].
-    fn default_style() -> Style<Self>;
+    fn default_style(&self, status: Status) -> Appearance;
 }
 
 impl DefaultStyle for Theme {
-    fn default_style() -> Style<Self> {
-        primary
+    fn default_style(&self, status: Status) -> Appearance {
+        primary(self, status)
     }
 }
 
 impl DefaultStyle for Appearance {
-    fn default_style() -> Style<Self> {
-        |appearance, _status| *appearance
+    fn default_style(&self, _status: Status) -> Appearance {
+        *self
     }
 }
 
diff --git a/widget/src/combo_box.rs b/widget/src/combo_box.rs
index bddf2789..ee24d742 100644
--- a/widget/src/combo_box.rs
+++ b/widget/src/combo_box.rs
@@ -42,7 +42,7 @@ pub struct ComboBox<
     on_option_hovered: Option<Box<dyn Fn(T) -> Message>>,
     on_close: Option<Message>,
     on_input: Option<Box<dyn Fn(String) -> Message>>,
-    menu_style: menu::Style<Theme>,
+    menu_style: menu::Style<'a, Theme>,
     padding: Padding,
     size: Option<f32>,
 }
@@ -62,7 +62,7 @@ where
         on_selected: impl Fn(T) -> Message + 'static,
     ) -> Self
     where
-        Theme: DefaultStyle,
+        Theme: DefaultStyle + 'a,
     {
         let style = Theme::default_style();
 
@@ -125,7 +125,10 @@ where
     }
 
     /// Sets the style of the [`ComboBox`].
-    pub fn style(mut self, style: impl Into<Style<Theme>>) -> Self {
+    pub fn style(mut self, style: impl Into<Style<'a, Theme>>) -> Self
+    where
+        Theme: 'a,
+    {
         let style = style.into();
 
         self.text_input = self.text_input.style(style.text_input);
@@ -669,7 +672,7 @@ where
 
             self.state.sync_filtered_options(filtered_options);
 
-            let mut menu = menu::Menu::with_style(
+            let mut menu = menu::Menu::new(
                 menu,
                 &filtered_options.options,
                 hovered_option,
@@ -683,7 +686,7 @@ where
                     (self.on_selected)(x)
                 },
                 self.on_option_hovered.as_deref(),
-                self.menu_style,
+                &self.menu_style,
             )
             .width(bounds.width)
             .padding(self.padding);
@@ -761,41 +764,28 @@ where
 }
 
 /// The style of a [`ComboBox`].
-#[derive(Debug, PartialEq, Eq)]
-pub struct Style<Theme> {
+#[allow(missing_debug_implementations)]
+pub struct Style<'a, Theme> {
     /// The style of the [`TextInput`] of the [`ComboBox`].
-    pub text_input: fn(&Theme, text_input::Status) -> text_input::Appearance,
+    pub text_input: text_input::Style<'a, Theme>,
 
     /// The style of the [`Menu`] of the [`ComboBox`].
     ///
     /// [`Menu`]: menu::Menu
-    pub menu: menu::Style<Theme>,
-}
-
-impl Style<Theme> {
-    /// The default style of a [`ComboBox`].
-    pub const DEFAULT: Self = Self {
-        text_input: text_input::default,
-        menu: menu::Style::<Theme>::DEFAULT,
-    };
+    pub menu: menu::Style<'a, Theme>,
 }
 
-impl<Theme> Clone for Style<Theme> {
-    fn clone(&self) -> Self {
-        *self
-    }
-}
-
-impl<Theme> Copy for Style<Theme> {}
-
 /// The default style of a [`ComboBox`].
 pub trait DefaultStyle: Sized {
     /// Returns the default style of a [`ComboBox`].
-    fn default_style() -> Style<Self>;
+    fn default_style() -> Style<'static, Self>;
 }
 
 impl DefaultStyle for Theme {
-    fn default_style() -> Style<Self> {
-        Style::<Self>::DEFAULT
+    fn default_style() -> Style<'static, Self> {
+        Style {
+            text_input: Box::new(text_input::default),
+            menu: menu::DefaultStyle::default_style(),
+        }
     }
 }
diff --git a/widget/src/container.rs b/widget/src/container.rs
index d606b0aa..7c133588 100644
--- a/widget/src/container.rs
+++ b/widget/src/container.rs
@@ -36,7 +36,7 @@ pub struct Container<
     vertical_alignment: alignment::Vertical,
     clip: bool,
     content: Element<'a, Message, Theme, Renderer>,
-    style: Style<Theme>,
+    style: Style<'a, Theme>,
 }
 
 impl<'a, Message, Theme, Renderer> Container<'a, Message, Theme, Renderer>
@@ -48,15 +48,15 @@ where
         content: impl Into<Element<'a, Message, Theme, Renderer>>,
     ) -> Self
     where
-        Theme: DefaultStyle,
+        Theme: DefaultStyle + 'a,
     {
-        Self::with_style(content, Theme::default_style())
+        Self::with_style(content, Theme::default_style)
     }
 
     /// Creates a [`Container`] with the given content and style.
     pub fn with_style(
         content: impl Into<Element<'a, Message, Theme, Renderer>>,
-        style: fn(&Theme, Status) -> Appearance,
+        style: impl Fn(&Theme, Status) -> Appearance + 'a,
     ) -> Self {
         let content = content.into();
         let size = content.as_widget().size_hint();
@@ -71,8 +71,8 @@ where
             horizontal_alignment: alignment::Horizontal::Left,
             vertical_alignment: alignment::Vertical::Top,
             clip: false,
+            style: Box::new(style),
             content,
-            style,
         }
     }
 
@@ -137,8 +137,11 @@ where
     }
 
     /// Sets the style of the [`Container`].
-    pub fn style(mut self, style: fn(&Theme, Status) -> Appearance) -> Self {
-        self.style = style;
+    pub fn style(
+        mut self,
+        style: impl Fn(&Theme, Status) -> Appearance + 'a,
+    ) -> Self {
+        self.style = Box::new(style);
         self
     }
 
@@ -536,6 +539,24 @@ impl Appearance {
     }
 }
 
+impl From<Color> for Appearance {
+    fn from(color: Color) -> Self {
+        Self::default().with_background(color)
+    }
+}
+
+impl From<Gradient> for Appearance {
+    fn from(gradient: Gradient) -> Self {
+        Self::default().with_background(gradient)
+    }
+}
+
+impl From<gradient::Linear> for Appearance {
+    fn from(gradient: gradient::Linear) -> Self {
+        Self::default().with_background(gradient)
+    }
+}
+
 /// The possible status of a [`Container`].
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum Status {
@@ -546,41 +567,41 @@ pub enum Status {
 }
 
 /// The style of a [`Container`].
-pub type Style<Theme> = fn(&Theme, Status) -> Appearance;
+pub type Style<'a, Theme> = Box<dyn Fn(&Theme, Status) -> Appearance + 'a>;
 
 /// The default style of a [`Container`].
 pub trait DefaultStyle {
     /// Returns the default style of a [`Container`].
-    fn default_style() -> Style<Self>;
+    fn default_style(&self, status: Status) -> Appearance;
 }
 
 impl DefaultStyle for Theme {
-    fn default_style() -> Style<Self> {
-        transparent
+    fn default_style(&self, status: Status) -> Appearance {
+        transparent(self, status)
     }
 }
 
 impl DefaultStyle for Appearance {
-    fn default_style() -> Style<Self> {
-        |appearance, _status| *appearance
+    fn default_style(&self, _status: Status) -> Appearance {
+        *self
     }
 }
 
 impl DefaultStyle for Color {
-    fn default_style() -> Style<Self> {
-        |color, _status| Appearance::default().with_background(*color)
+    fn default_style(&self, _status: Status) -> Appearance {
+        Appearance::from(*self)
     }
 }
 
 impl DefaultStyle for Gradient {
-    fn default_style() -> Style<Self> {
-        |gradient, _status| Appearance::default().with_background(*gradient)
+    fn default_style(&self, _status: Status) -> Appearance {
+        Appearance::from(*self)
     }
 }
 
 impl DefaultStyle for gradient::Linear {
-    fn default_style() -> Style<Self> {
-        |gradient, _status| Appearance::default().with_background(*gradient)
+    fn default_style(&self, _status: Status) -> Appearance {
+        Appearance::from(*self)
     }
 }
 
diff --git a/widget/src/helpers.rs b/widget/src/helpers.rs
index 75072d2e..4863e550 100644
--- a/widget/src/helpers.rs
+++ b/widget/src/helpers.rs
@@ -14,7 +14,7 @@ use crate::rule::{self, Rule};
 use crate::runtime::Command;
 use crate::scrollable::{self, Scrollable};
 use crate::slider::{self, Slider};
-use crate::text::Text;
+use crate::text::{self, Text};
 use crate::text_editor::{self, TextEditor};
 use crate::text_input::{self, TextInput};
 use crate::toggler::{self, Toggler};
@@ -58,7 +58,7 @@ pub fn container<'a, Message, Theme, Renderer>(
     content: impl Into<Element<'a, Message, Theme, Renderer>>,
 ) -> Container<'a, Message, Theme, Renderer>
 where
-    Theme: container::DefaultStyle,
+    Theme: container::DefaultStyle + 'a,
     Renderer: core::Renderer,
 {
     Container::new(content)
@@ -104,7 +104,7 @@ pub fn scrollable<'a, Message, Theme, Renderer>(
     content: impl Into<Element<'a, Message, Theme, Renderer>>,
 ) -> Scrollable<'a, Message, Theme, Renderer>
 where
-    Theme: scrollable::DefaultStyle,
+    Theme: scrollable::DefaultStyle + 'a,
     Renderer: core::Renderer,
 {
     Scrollable::new(content)
@@ -117,7 +117,7 @@ pub fn button<'a, Message, Theme, Renderer>(
     content: impl Into<Element<'a, Message, Theme, Renderer>>,
 ) -> Button<'a, Message, Theme, Renderer>
 where
-    Theme: button::DefaultStyle,
+    Theme: button::DefaultStyle + 'a,
     Renderer: core::Renderer,
 {
     Button::new(content)
@@ -134,7 +134,7 @@ pub fn tooltip<'a, Message, Theme, Renderer>(
     position: tooltip::Position,
 ) -> crate::Tooltip<'a, Message, Theme, Renderer>
 where
-    Theme: container::DefaultStyle,
+    Theme: container::DefaultStyle + 'a,
     Renderer: core::text::Renderer,
 {
     Tooltip::new(content, tooltip, position)
@@ -147,6 +147,7 @@ pub fn text<'a, Theme, Renderer>(
     text: impl ToString,
 ) -> Text<'a, Theme, Renderer>
 where
+    Theme: text::DefaultStyle + 'a,
     Renderer: core::text::Renderer,
 {
     Text::new(text.to_string())
@@ -160,7 +161,7 @@ pub fn checkbox<'a, Message, Theme, Renderer>(
     is_checked: bool,
 ) -> Checkbox<'a, Message, Theme, Renderer>
 where
-    Theme: checkbox::DefaultStyle,
+    Theme: checkbox::DefaultStyle + 'a,
     Renderer: core::text::Renderer,
 {
     Checkbox::new(label, is_checked)
@@ -169,15 +170,15 @@ where
 /// Creates a new [`Radio`].
 ///
 /// [`Radio`]: crate::Radio
-pub fn radio<Message, Theme, Renderer, V>(
+pub fn radio<'a, Message, Theme, Renderer, V>(
     label: impl Into<String>,
     value: V,
     selected: Option<V>,
     on_click: impl FnOnce(V) -> Message,
-) -> Radio<Message, Theme, Renderer>
+) -> Radio<'a, Message, Theme, Renderer>
 where
     Message: Clone,
-    Theme: radio::DefaultStyle,
+    Theme: radio::DefaultStyle + 'a,
     Renderer: core::text::Renderer,
     V: Copy + Eq,
 {
@@ -193,7 +194,7 @@ pub fn toggler<'a, Message, Theme, Renderer>(
     f: impl Fn(bool) -> Message + 'a,
 ) -> Toggler<'a, Message, Theme, Renderer>
 where
-    Theme: toggler::DefaultStyle,
+    Theme: toggler::DefaultStyle + 'a,
     Renderer: core::text::Renderer,
 {
     Toggler::new(label, is_checked, f)
@@ -208,7 +209,7 @@ pub fn text_input<'a, Message, Theme, Renderer>(
 ) -> TextInput<'a, Message, Theme, Renderer>
 where
     Message: Clone,
-    Theme: text_input::DefaultStyle,
+    Theme: text_input::DefaultStyle + 'a,
     Renderer: core::text::Renderer,
 {
     TextInput::new(placeholder, value)
@@ -217,12 +218,12 @@ where
 /// Creates a new [`TextEditor`].
 ///
 /// [`TextEditor`]: crate::TextEditor
-pub fn text_editor<Message, Theme, Renderer>(
-    content: &text_editor::Content<Renderer>,
-) -> TextEditor<'_, core::text::highlighter::PlainText, Message, Theme, Renderer>
+pub fn text_editor<'a, Message, Theme, Renderer>(
+    content: &'a text_editor::Content<Renderer>,
+) -> TextEditor<'a, core::text::highlighter::PlainText, Message, Theme, Renderer>
 where
     Message: Clone,
-    Theme: text_editor::DefaultStyle,
+    Theme: text_editor::DefaultStyle + 'a,
     Renderer: core::text::Renderer,
 {
     TextEditor::new(content)
@@ -239,7 +240,7 @@ pub fn slider<'a, T, Message, Theme>(
 where
     T: Copy + From<u8> + std::cmp::PartialOrd,
     Message: Clone,
-    Theme: slider::DefaultStyle,
+    Theme: slider::DefaultStyle + 'a,
 {
     Slider::new(range, value, on_change)
 }
@@ -255,7 +256,7 @@ pub fn vertical_slider<'a, T, Message, Theme>(
 where
     T: Copy + From<u8> + std::cmp::PartialOrd,
     Message: Clone,
-    Theme: vertical_slider::DefaultStyle,
+    Theme: vertical_slider::DefaultStyle + 'a,
 {
     VerticalSlider::new(range, value, on_change)
 }
@@ -290,7 +291,7 @@ pub fn combo_box<'a, T, Message, Theme, Renderer>(
 ) -> ComboBox<'a, T, Message, Theme, Renderer>
 where
     T: std::fmt::Display + Clone,
-    Theme: combo_box::DefaultStyle,
+    Theme: combo_box::DefaultStyle + 'a,
     Renderer: core::text::Renderer,
 {
     ComboBox::new(state, placeholder, selection, on_selected)
@@ -315,9 +316,9 @@ pub fn vertical_space() -> Space {
 /// Creates a horizontal [`Rule`] with the given height.
 ///
 /// [`Rule`]: crate::Rule
-pub fn horizontal_rule<Theme>(height: impl Into<Pixels>) -> Rule<Theme>
+pub fn horizontal_rule<'a, Theme>(height: impl Into<Pixels>) -> Rule<'a, Theme>
 where
-    Theme: rule::DefaultStyle,
+    Theme: rule::DefaultStyle + 'a,
 {
     Rule::horizontal(height)
 }
@@ -325,9 +326,9 @@ where
 /// Creates a vertical [`Rule`] with the given width.
 ///
 /// [`Rule`]: crate::Rule
-pub fn vertical_rule<Theme>(width: impl Into<Pixels>) -> Rule<Theme>
+pub fn vertical_rule<'a, Theme>(width: impl Into<Pixels>) -> Rule<'a, Theme>
 where
-    Theme: rule::DefaultStyle,
+    Theme: rule::DefaultStyle + 'a,
 {
     Rule::vertical(width)
 }
@@ -339,12 +340,12 @@ where
 ///   * the current value of the [`ProgressBar`].
 ///
 /// [`ProgressBar`]: crate::ProgressBar
-pub fn progress_bar<Theme>(
+pub fn progress_bar<'a, Theme>(
     range: RangeInclusive<f32>,
     value: f32,
-) -> ProgressBar<Theme>
+) -> ProgressBar<'a, Theme>
 where
-    Theme: progress_bar::DefaultStyle,
+    Theme: progress_bar::DefaultStyle + 'a,
 {
     ProgressBar::new(range, value)
 }
@@ -362,9 +363,11 @@ pub fn image<Handle>(handle: impl Into<Handle>) -> crate::Image<Handle> {
 /// [`Svg`]: crate::Svg
 /// [`Handle`]: crate::svg::Handle
 #[cfg(feature = "svg")]
-pub fn svg<Theme>(handle: impl Into<core::svg::Handle>) -> crate::Svg<Theme>
+pub fn svg<'a, Theme>(
+    handle: impl Into<core::svg::Handle>,
+) -> crate::Svg<'a, Theme>
 where
-    Theme: crate::svg::DefaultStyle,
+    Theme: crate::svg::DefaultStyle + 'a,
 {
     crate::Svg::new(handle)
 }
@@ -388,9 +391,11 @@ where
 /// [`QRCode`]: crate::QRCode
 /// [`Data`]: crate::qr_code::Data
 #[cfg(feature = "qr_code")]
-pub fn qr_code<Theme>(data: &crate::qr_code::Data) -> crate::QRCode<'_, Theme>
+pub fn qr_code<'a, Theme>(
+    data: &'a crate::qr_code::Data,
+) -> crate::QRCode<'a, Theme>
 where
-    Theme: crate::qr_code::DefaultStyle,
+    Theme: crate::qr_code::DefaultStyle + 'a,
 {
     crate::QRCode::new(data)
 }
diff --git a/widget/src/overlay/menu.rs b/widget/src/overlay/menu.rs
index 746407c6..0364f980 100644
--- a/widget/src/overlay/menu.rs
+++ b/widget/src/overlay/menu.rs
@@ -38,7 +38,7 @@ pub struct Menu<
     text_line_height: text::LineHeight,
     text_shaping: text::Shaping,
     font: Option<Renderer::Font>,
-    style: Style<Theme>,
+    style: &'a Style<'a, Theme>,
 }
 
 impl<'a, T, Message, Theme, Renderer> Menu<'a, T, Message, Theme, Renderer>
@@ -48,37 +48,15 @@ where
     Theme: 'a,
     Renderer: text::Renderer + 'a,
 {
-    /// Creates a new [`Menu`] with the given [`State`], a list of options, and
-    /// the message to produced when an option is selected.
-    pub fn new(
-        state: &'a mut State,
-        options: &'a [T],
-        hovered_option: &'a mut Option<usize>,
-        on_selected: impl FnMut(T) -> Message + 'a,
-        on_option_hovered: Option<&'a dyn Fn(T) -> Message>,
-    ) -> Self
-    where
-        Theme: DefaultStyle,
-    {
-        Self::with_style(
-            state,
-            options,
-            hovered_option,
-            on_selected,
-            on_option_hovered,
-            Theme::default_style(),
-        )
-    }
-
     /// Creates a new [`Menu`] with the given [`State`], a list of options,
     /// the message to produced when an option is selected, and its [`Style`].
-    pub fn with_style(
+    pub fn new(
         state: &'a mut State,
         options: &'a [T],
         hovered_option: &'a mut Option<usize>,
         on_selected: impl FnMut(T) -> Message + 'a,
         on_option_hovered: Option<&'a dyn Fn(T) -> Message>,
-        style: Style<Theme>,
+        style: &'a Style<'a, Theme>,
     ) -> Self {
         Menu {
             state,
@@ -135,12 +113,6 @@ where
         self
     }
 
-    /// Sets the style of the [`Menu`].
-    pub fn style(mut self, style: impl Into<Style<Theme>>) -> Self {
-        self.style = style.into();
-        self
-    }
-
     /// Turns the [`Menu`] into an overlay [`Element`] at the given target
     /// position.
     ///
@@ -190,7 +162,7 @@ where
     container: Container<'a, Message, Theme, Renderer>,
     width: f32,
     target_height: f32,
-    style: Style<Theme>,
+    style: &'a Style<'a, Theme>,
 }
 
 impl<'a, Message, Theme, Renderer> Overlay<'a, Message, Theme, Renderer>
@@ -234,10 +206,10 @@ where
                     text_line_height,
                     text_shaping,
                     padding,
-                    style: style.list,
+                    style: &style.list,
                 },
                 scrollable::Direction::default(),
-                style.scrollable,
+                &style.scrollable,
             ),
             container::transparent,
         );
@@ -356,7 +328,7 @@ where
     text_line_height: text::LineHeight,
     text_shaping: text::Shaping,
     font: Option<Renderer::Font>,
-    style: fn(&Theme) -> Appearance,
+    style: &'a dyn Fn(&Theme) -> Appearance,
 }
 
 impl<'a, T, Message, Theme, Renderer> Widget<Message, Theme, Renderer>
@@ -599,39 +571,26 @@ pub struct Appearance {
 }
 
 /// The style of the different parts of a [`Menu`].
-#[derive(Debug, PartialEq, Eq)]
-pub struct Style<Theme> {
+#[allow(missing_debug_implementations)]
+pub struct Style<'a, Theme> {
     /// The style of the list of the [`Menu`].
-    pub list: fn(&Theme) -> Appearance,
+    pub list: Box<dyn Fn(&Theme) -> Appearance + 'a>,
     /// The style of the [`Scrollable`] of the [`Menu`].
-    pub scrollable: fn(&Theme, scrollable::Status) -> scrollable::Appearance,
+    pub scrollable: scrollable::Style<'a, Theme>,
 }
 
-impl Style<Theme> {
-    /// The default style of a [`Menu`] with the built-in [`Theme`].
-    pub const DEFAULT: Self = Self {
-        list: default,
-        scrollable: scrollable::default,
-    };
-}
-
-impl<Theme> Clone for Style<Theme> {
-    fn clone(&self) -> Self {
-        *self
-    }
-}
-
-impl<Theme> Copy for Style<Theme> {}
-
 /// The default style of a [`Menu`].
 pub trait DefaultStyle: Sized {
     /// Returns the default style of a [`Menu`].
-    fn default_style() -> Style<Self>;
+    fn default_style() -> Style<'static, Self>;
 }
 
 impl DefaultStyle for Theme {
-    fn default_style() -> Style<Self> {
-        Style::<Theme>::DEFAULT
+    fn default_style() -> Style<'static, Self> {
+        Style {
+            list: Box::new(default),
+            scrollable: Box::new(scrollable::default),
+        }
     }
 }
 
diff --git a/widget/src/pane_grid.rs b/widget/src/pane_grid.rs
index bdeb4250..beac0bd8 100644
--- a/widget/src/pane_grid.rs
+++ b/widget/src/pane_grid.rs
@@ -110,7 +110,7 @@ pub struct PaneGrid<
     on_click: Option<Box<dyn Fn(Pane) -> Message + 'a>>,
     on_drag: Option<Box<dyn Fn(DragEvent) -> Message + 'a>>,
     on_resize: Option<(f32, Box<dyn Fn(ResizeEvent) -> Message + 'a>)>,
-    style: Style<Theme>,
+    style: Style<'a, Theme>,
 }
 
 impl<'a, Message, Theme, Renderer> PaneGrid<'a, Message, Theme, Renderer>
@@ -126,7 +126,7 @@ where
         view: impl Fn(Pane, &'a T, bool) -> Content<'a, Message, Theme, Renderer>,
     ) -> Self
     where
-        Theme: DefaultStyle,
+        Theme: DefaultStyle + 'a,
     {
         let contents = if let Some((pane, pane_state)) =
             state.maximized.and_then(|pane| {
@@ -158,7 +158,7 @@ where
             on_click: None,
             on_drag: None,
             on_resize: None,
-            style: Theme::default_style(),
+            style: Box::new(Theme::default_style),
         }
     }
 
@@ -218,8 +218,8 @@ where
     }
 
     /// Sets the style of the [`PaneGrid`].
-    pub fn style(mut self, style: fn(&Theme) -> Appearance) -> Self {
-        self.style = style;
+    pub fn style(mut self, style: impl Fn(&Theme) -> Appearance + 'a) -> Self {
+        self.style = Box::new(style);
         self
     }
 
@@ -1146,23 +1146,23 @@ pub struct Line {
 }
 
 /// The style of a [`PaneGrid`].
-pub type Style<Theme> = fn(&Theme) -> Appearance;
+pub type Style<'a, Theme> = Box<dyn Fn(&Theme) -> Appearance + 'a>;
 
 /// The default style of a [`PaneGrid`].
 pub trait DefaultStyle {
     /// Returns the default style of a [`PaneGrid`].
-    fn default_style() -> Style<Self>;
+    fn default_style(&self) -> Appearance;
 }
 
 impl DefaultStyle for Theme {
-    fn default_style() -> Style<Self> {
-        default
+    fn default_style(&self) -> Appearance {
+        default(self)
     }
 }
 
 impl DefaultStyle for Appearance {
-    fn default_style() -> Style<Self> {
-        |appearance| *appearance
+    fn default_style(&self) -> Appearance {
+        *self
     }
 }
 
diff --git a/widget/src/pane_grid/content.rs b/widget/src/pane_grid/content.rs
index aecec777..98f4f99a 100644
--- a/widget/src/pane_grid/content.rs
+++ b/widget/src/pane_grid/content.rs
@@ -24,7 +24,7 @@ pub struct Content<
 {
     title_bar: Option<TitleBar<'a, Message, Theme, Renderer>>,
     body: Element<'a, Message, Theme, Renderer>,
-    style: container::Style<Theme>,
+    style: container::Style<'a, Theme>,
 }
 
 impl<'a, Message, Theme, Renderer> Content<'a, Message, Theme, Renderer>
@@ -34,12 +34,12 @@ where
     /// Creates a new [`Content`] with the provided body.
     pub fn new(body: impl Into<Element<'a, Message, Theme, Renderer>>) -> Self
     where
-        Theme: container::DefaultStyle,
+        Theme: container::DefaultStyle + 'a,
     {
         Self {
             title_bar: None,
             body: body.into(),
-            style: Theme::default_style(),
+            style: Box::new(Theme::default_style),
         }
     }
 
@@ -55,9 +55,9 @@ where
     /// Sets the style of the [`Content`].
     pub fn style(
         mut self,
-        style: fn(&Theme, container::Status) -> container::Appearance,
+        style: impl Fn(&Theme, container::Status) -> container::Appearance + 'a,
     ) -> Self {
-        self.style = style.into();
+        self.style = Box::new(style);
         self
     }
 }
@@ -403,7 +403,7 @@ impl<'a, T, Message, Theme, Renderer> From<T>
     for Content<'a, Message, Theme, Renderer>
 where
     T: Into<Element<'a, Message, Theme, Renderer>>,
-    Theme: container::DefaultStyle,
+    Theme: container::DefaultStyle + 'a,
     Renderer: crate::core::Renderer,
 {
     fn from(element: T) -> Self {
diff --git a/widget/src/pane_grid/title_bar.rs b/widget/src/pane_grid/title_bar.rs
index 37f0f160..8dfea6e3 100644
--- a/widget/src/pane_grid/title_bar.rs
+++ b/widget/src/pane_grid/title_bar.rs
@@ -25,7 +25,7 @@ pub struct TitleBar<
     controls: Option<Element<'a, Message, Theme, Renderer>>,
     padding: Padding,
     always_show_controls: bool,
-    style: container::Style<Theme>,
+    style: container::Style<'a, Theme>,
 }
 
 impl<'a, Message, Theme, Renderer> TitleBar<'a, Message, Theme, Renderer>
@@ -37,14 +37,14 @@ where
         content: impl Into<Element<'a, Message, Theme, Renderer>>,
     ) -> Self
     where
-        Theme: container::DefaultStyle,
+        Theme: container::DefaultStyle + 'a,
     {
         Self {
             content: content.into(),
             controls: None,
             padding: Padding::ZERO,
             always_show_controls: false,
-            style: Theme::default_style(),
+            style: Box::new(Theme::default_style),
         }
     }
 
@@ -66,9 +66,9 @@ where
     /// Sets the style of the [`TitleBar`].
     pub fn style(
         mut self,
-        style: fn(&Theme, container::Status) -> container::Appearance,
+        style: impl Fn(&Theme, container::Status) -> container::Appearance + 'a,
     ) -> Self {
-        self.style = style.into();
+        self.style = Box::new(style);
         self
     }
 
diff --git a/widget/src/pick_list.rs b/widget/src/pick_list.rs
index beb4e0c1..52d54397 100644
--- a/widget/src/pick_list.rs
+++ b/widget/src/pick_list.rs
@@ -47,7 +47,7 @@ pub struct PickList<
     text_shaping: text::Shaping,
     font: Option<Renderer::Font>,
     handle: Handle<Renderer::Font>,
-    style: Style<Theme>,
+    style: Style<'a, Theme>,
 }
 
 impl<'a, T, L, V, Message, Theme, Renderer>
@@ -151,7 +151,7 @@ where
     }
 
     /// Sets the style of the [`PickList`].
-    pub fn style(mut self, style: impl Into<Style<Theme>>) -> Self {
+    pub fn style(mut self, style: impl Into<Style<'a, Theme>>) -> Self {
         self.style = style.into();
         self
     }
@@ -529,7 +529,7 @@ where
 
             let on_select = &self.on_select;
 
-            let mut menu = Menu::with_style(
+            let mut menu = Menu::new(
                 &mut state.menu,
                 self.options.borrow(),
                 &mut state.hovered_option,
@@ -539,7 +539,7 @@ where
                     (on_select)(option)
                 },
                 None,
-                self.style.menu,
+                &self.style.menu,
             )
             .width(bounds.width)
             .padding(self.padding)
@@ -676,40 +676,27 @@ pub struct Appearance {
 }
 
 /// The styles of the different parts of a [`PickList`].
-#[derive(Debug, PartialEq, Eq)]
-pub struct Style<Theme> {
+#[allow(missing_debug_implementations)]
+pub struct Style<'a, Theme> {
     /// The style of the [`PickList`] itself.
-    pub field: fn(&Theme, Status) -> Appearance,
+    pub field: Box<dyn Fn(&Theme, Status) -> Appearance + 'a>,
 
     /// The style of the [`Menu`] of the pick list.
-    pub menu: menu::Style<Theme>,
+    pub menu: menu::Style<'a, Theme>,
 }
 
-impl Style<Theme> {
-    /// The default style of a [`PickList`] with the built-in [`Theme`].
-    pub const DEFAULT: Self = Self {
-        field: default,
-        menu: menu::Style::<Theme>::DEFAULT,
-    };
-}
-
-impl<Theme> Clone for Style<Theme> {
-    fn clone(&self) -> Self {
-        *self
-    }
-}
-
-impl<Theme> Copy for Style<Theme> {}
-
 /// The default style of a [`PickList`].
 pub trait DefaultStyle: Sized {
     /// Returns the default style of a [`PickList`].
-    fn default_style() -> Style<Self>;
+    fn default_style() -> Style<'static, Self>;
 }
 
 impl DefaultStyle for Theme {
-    fn default_style() -> Style<Self> {
-        Style::<Self>::DEFAULT
+    fn default_style() -> Style<'static, Self> {
+        Style {
+            field: Box::new(default),
+            menu: menu::DefaultStyle::default_style(),
+        }
     }
 }
 
diff --git a/widget/src/progress_bar.rs b/widget/src/progress_bar.rs
index 7b0ea63f..38d8da85 100644
--- a/widget/src/progress_bar.rs
+++ b/widget/src/progress_bar.rs
@@ -13,7 +13,7 @@ use std::ops::RangeInclusive;
 ///
 /// # Example
 /// ```no_run
-/// # type ProgressBar = iced_widget::ProgressBar;
+/// # type ProgressBar<'a> = iced_widget::ProgressBar<'a>;
 /// #
 /// let value = 50.0;
 ///
@@ -22,15 +22,15 @@ use std::ops::RangeInclusive;
 ///
 /// ![Progress bar drawn with `iced_wgpu`](https://user-images.githubusercontent.com/18618951/71662391-a316c200-2d51-11ea-9cef-52758cab85e3.png)
 #[allow(missing_debug_implementations)]
-pub struct ProgressBar<Theme = crate::Theme> {
+pub struct ProgressBar<'a, Theme = crate::Theme> {
     range: RangeInclusive<f32>,
     value: f32,
     width: Length,
     height: Option<Length>,
-    style: Style<Theme>,
+    style: Style<'a, Theme>,
 }
 
-impl<Theme> ProgressBar<Theme> {
+impl<'a, Theme> ProgressBar<'a, Theme> {
     /// The default height of a [`ProgressBar`].
     pub const DEFAULT_HEIGHT: f32 = 30.0;
 
@@ -41,14 +41,14 @@ impl<Theme> ProgressBar<Theme> {
     ///   * the current value of the [`ProgressBar`]
     pub fn new(range: RangeInclusive<f32>, value: f32) -> Self
     where
-        Theme: DefaultStyle,
+        Theme: DefaultStyle + 'a,
     {
         ProgressBar {
             value: value.clamp(*range.start(), *range.end()),
             range,
             width: Length::Fill,
             height: None,
-            style: Theme::default_style(),
+            style: Box::new(Theme::default_style),
         }
     }
 
@@ -65,14 +65,14 @@ impl<Theme> ProgressBar<Theme> {
     }
 
     /// Sets the style of the [`ProgressBar`].
-    pub fn style(mut self, style: fn(&Theme) -> Appearance) -> Self {
-        self.style = style.into();
+    pub fn style(mut self, style: impl Fn(&Theme) -> Appearance + 'a) -> Self {
+        self.style = Box::new(style);
         self
     }
 }
 
-impl<Message, Theme, Renderer> Widget<Message, Theme, Renderer>
-    for ProgressBar<Theme>
+impl<'a, Message, Theme, Renderer> Widget<Message, Theme, Renderer>
+    for ProgressBar<'a, Theme>
 where
     Renderer: crate::core::Renderer,
 {
@@ -143,7 +143,7 @@ where
     }
 }
 
-impl<'a, Message, Theme, Renderer> From<ProgressBar<Theme>>
+impl<'a, Message, Theme, Renderer> From<ProgressBar<'a, Theme>>
     for Element<'a, Message, Theme, Renderer>
 where
     Message: 'a,
@@ -151,7 +151,7 @@ where
     Renderer: 'a + crate::core::Renderer,
 {
     fn from(
-        progress_bar: ProgressBar<Theme>,
+        progress_bar: ProgressBar<'a, Theme>,
     ) -> Element<'a, Message, Theme, Renderer> {
         Element::new(progress_bar)
     }
@@ -169,23 +169,23 @@ pub struct Appearance {
 }
 
 /// The style of a [`ProgressBar`].
-pub type Style<Theme> = fn(&Theme) -> Appearance;
+pub type Style<'a, Theme> = Box<dyn Fn(&Theme) -> Appearance + 'a>;
 
 /// The default style of a [`ProgressBar`].
 pub trait DefaultStyle {
     /// Returns the default style of a [`ProgressBar`].
-    fn default_style() -> Style<Self>;
+    fn default_style(&self) -> Appearance;
 }
 
 impl DefaultStyle for Theme {
-    fn default_style() -> Style<Self> {
-        primary
+    fn default_style(&self) -> Appearance {
+        primary(self)
     }
 }
 
 impl DefaultStyle for Appearance {
-    fn default_style() -> Style<Self> {
-        |appearance| *appearance
+    fn default_style(&self) -> Appearance {
+        *self
     }
 }
 
diff --git a/widget/src/qr_code.rs b/widget/src/qr_code.rs
index 41bcb83e..90c0c970 100644
--- a/widget/src/qr_code.rs
+++ b/widget/src/qr_code.rs
@@ -19,23 +19,23 @@ const QUIET_ZONE: usize = 2;
 
 /// A type of matrix barcode consisting of squares arranged in a grid which
 /// can be read by an imaging device, such as a camera.
-#[derive(Debug)]
+#[allow(missing_debug_implementations)]
 pub struct QRCode<'a, Theme = crate::Theme> {
     data: &'a Data,
     cell_size: u16,
-    style: Style<Theme>,
+    style: Style<'a, Theme>,
 }
 
 impl<'a, Theme> QRCode<'a, Theme> {
     /// Creates a new [`QRCode`] with the provided [`Data`].
     pub fn new(data: &'a Data) -> Self
     where
-        Theme: DefaultStyle,
+        Theme: DefaultStyle + 'a,
     {
         Self {
             data,
             cell_size: DEFAULT_CELL_SIZE,
-            style: Theme::default_style(),
+            style: Box::new(Theme::default_style),
         }
     }
 
@@ -46,8 +46,8 @@ impl<'a, Theme> QRCode<'a, Theme> {
     }
 
     /// Sets the style of the [`QRCode`].
-    pub fn style(mut self, style: fn(&Theme) -> Appearance) -> Self {
-        self.style = style.into();
+    pub fn style(mut self, style: impl Fn(&Theme) -> Appearance + 'a) -> Self {
+        self.style = Box::new(style);
         self
     }
 }
@@ -336,23 +336,23 @@ pub struct Appearance {
 }
 
 /// The style of a [`QRCode`].
-pub type Style<Theme> = fn(&Theme) -> Appearance;
+pub type Style<'a, Theme> = Box<dyn Fn(&Theme) -> Appearance + 'a>;
 
 /// The default style of a [`QRCode`].
 pub trait DefaultStyle {
     /// Returns the default style of a [`QRCode`].
-    fn default_style() -> Style<Self>;
+    fn default_style(&self) -> Appearance;
 }
 
 impl DefaultStyle for Theme {
-    fn default_style() -> Style<Self> {
-        default
+    fn default_style(&self) -> Appearance {
+        default(self)
     }
 }
 
 impl DefaultStyle for Appearance {
-    fn default_style() -> Style<Self> {
-        |appearance| *appearance
+    fn default_style(&self) -> Appearance {
+        *self
     }
 }
 
diff --git a/widget/src/radio.rs b/widget/src/radio.rs
index 5e4a3c1f..a7b7dd03 100644
--- a/widget/src/radio.rs
+++ b/widget/src/radio.rs
@@ -17,8 +17,8 @@ use crate::core::{
 ///
 /// # Example
 /// ```no_run
-/// # type Radio<Message> =
-/// #     iced_widget::Radio<Message, iced_widget::Theme, iced_widget::renderer::Renderer>;
+/// # type Radio<'a, Message> =
+/// #     iced_widget::Radio<'a, Message, iced_widget::Theme, iced_widget::renderer::Renderer>;
 /// #
 /// # use iced_widget::column;
 /// #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -67,7 +67,7 @@ use crate::core::{
 /// let content = column![a, b, c, all];
 /// ```
 #[allow(missing_debug_implementations)]
-pub struct Radio<Message, Theme = crate::Theme, Renderer = crate::Renderer>
+pub struct Radio<'a, Message, Theme = crate::Theme, Renderer = crate::Renderer>
 where
     Renderer: text::Renderer,
 {
@@ -81,10 +81,10 @@ where
     text_line_height: text::LineHeight,
     text_shaping: text::Shaping,
     font: Option<Renderer::Font>,
-    style: Style<Theme>,
+    style: Style<'a, Theme>,
 }
 
-impl<Message, Theme, Renderer> Radio<Message, Theme, Renderer>
+impl<'a, Message, Theme, Renderer> Radio<'a, Message, Theme, Renderer>
 where
     Message: Clone,
     Renderer: text::Renderer,
@@ -110,7 +110,7 @@ where
         f: F,
     ) -> Self
     where
-        Theme: DefaultStyle,
+        Theme: DefaultStyle + 'a,
         V: Eq + Copy,
         F: FnOnce(V) -> Message,
     {
@@ -125,7 +125,7 @@ where
             text_line_height: text::LineHeight::default(),
             text_shaping: text::Shaping::Basic,
             font: None,
-            style: Theme::default_style(),
+            style: Box::new(Theme::default_style),
         }
     }
 
@@ -175,14 +175,17 @@ where
     }
 
     /// Sets the style of the [`Radio`] button.
-    pub fn style(mut self, style: fn(&Theme, Status) -> Appearance) -> Self {
-        self.style = style;
+    pub fn style(
+        mut self,
+        style: impl Fn(&Theme, Status) -> Appearance + 'a,
+    ) -> Self {
+        self.style = Box::new(style);
         self
     }
 }
 
-impl<Message, Theme, Renderer> Widget<Message, Theme, Renderer>
-    for Radio<Message, Theme, Renderer>
+impl<'a, Message, Theme, Renderer> Widget<Message, Theme, Renderer>
+    for Radio<'a, Message, Theme, Renderer>
 where
     Message: Clone,
     Renderer: text::Renderer,
@@ -353,7 +356,7 @@ where
     }
 }
 
-impl<'a, Message, Theme, Renderer> From<Radio<Message, Theme, Renderer>>
+impl<'a, Message, Theme, Renderer> From<Radio<'a, Message, Theme, Renderer>>
     for Element<'a, Message, Theme, Renderer>
 where
     Message: 'a + Clone,
@@ -361,7 +364,7 @@ where
     Renderer: 'a + text::Renderer,
 {
     fn from(
-        radio: Radio<Message, Theme, Renderer>,
+        radio: Radio<'a, Message, Theme, Renderer>,
     ) -> Element<'a, Message, Theme, Renderer> {
         Element::new(radio)
     }
@@ -398,23 +401,23 @@ pub struct Appearance {
 }
 
 /// The style of a [`Radio`] button.
-pub type Style<Theme> = fn(&Theme, Status) -> Appearance;
+pub type Style<'a, Theme> = Box<dyn Fn(&Theme, Status) -> Appearance + 'a>;
 
 /// The default style of a [`Radio`] button.
 pub trait DefaultStyle {
     /// Returns the default style of a [`Radio`] button.
-    fn default_style() -> Style<Self>;
+    fn default_style(&self, status: Status) -> Appearance;
 }
 
 impl DefaultStyle for Theme {
-    fn default_style() -> Style<Self> {
-        default
+    fn default_style(&self, status: Status) -> Appearance {
+        default(self, status)
     }
 }
 
 impl DefaultStyle for Appearance {
-    fn default_style() -> Style<Self> {
-        |appearance, _status| *appearance
+    fn default_style(&self, _status: Status) -> Appearance {
+        *self
     }
 }
 
diff --git a/widget/src/rule.rs b/widget/src/rule.rs
index 8580d4c7..9fa5f74f 100644
--- a/widget/src/rule.rs
+++ b/widget/src/rule.rs
@@ -10,48 +10,49 @@ use crate::core::{
 
 /// Display a horizontal or vertical rule for dividing content.
 #[allow(missing_debug_implementations)]
-pub struct Rule<Theme = crate::Theme> {
+pub struct Rule<'a, Theme = crate::Theme> {
     width: Length,
     height: Length,
     is_horizontal: bool,
-    style: Style<Theme>,
+    style: Style<'a, Theme>,
 }
 
-impl<Theme> Rule<Theme> {
+impl<'a, Theme> Rule<'a, Theme> {
     /// Creates a horizontal [`Rule`] with the given height.
     pub fn horizontal(height: impl Into<Pixels>) -> Self
     where
-        Theme: DefaultStyle,
+        Theme: DefaultStyle + 'a,
     {
         Rule {
             width: Length::Fill,
             height: Length::Fixed(height.into().0),
             is_horizontal: true,
-            style: Theme::default_style(),
+            style: Box::new(Theme::default_style),
         }
     }
 
     /// Creates a vertical [`Rule`] with the given width.
     pub fn vertical(width: impl Into<Pixels>) -> Self
     where
-        Theme: DefaultStyle,
+        Theme: DefaultStyle + 'a,
     {
         Rule {
             width: Length::Fixed(width.into().0),
             height: Length::Fill,
             is_horizontal: false,
-            style: Theme::default_style(),
+            style: Box::new(Theme::default_style),
         }
     }
 
     /// Sets the style of the [`Rule`].
-    pub fn style(mut self, style: fn(&Theme) -> Appearance) -> Self {
-        self.style = style;
+    pub fn style(mut self, style: impl Fn(&Theme) -> Appearance + 'a) -> Self {
+        self.style = Box::new(style);
         self
     }
 }
 
-impl<Message, Theme, Renderer> Widget<Message, Theme, Renderer> for Rule<Theme>
+impl<'a, Message, Theme, Renderer> Widget<Message, Theme, Renderer>
+    for Rule<'a, Theme>
 where
     Renderer: crate::core::Renderer,
 {
@@ -126,14 +127,14 @@ where
     }
 }
 
-impl<'a, Message, Theme, Renderer> From<Rule<Theme>>
+impl<'a, Message, Theme, Renderer> From<Rule<'a, Theme>>
     for Element<'a, Message, Theme, Renderer>
 where
     Message: 'a,
     Theme: 'a,
     Renderer: 'a + crate::core::Renderer,
 {
-    fn from(rule: Rule<Theme>) -> Element<'a, Message, Theme, Renderer> {
+    fn from(rule: Rule<'a, Theme>) -> Element<'a, Message, Theme, Renderer> {
         Element::new(rule)
     }
 }
@@ -216,23 +217,23 @@ impl FillMode {
 }
 
 /// The style of a [`Rule`].
-pub type Style<Theme> = fn(&Theme) -> Appearance;
+pub type Style<'a, Theme> = Box<dyn Fn(&Theme) -> Appearance + 'a>;
 
 /// The default style of a [`Rule`].
 pub trait DefaultStyle {
     /// Returns the default style of a [`Rule`].
-    fn default_style() -> Style<Self>;
+    fn default_style(&self) -> Appearance;
 }
 
 impl DefaultStyle for Theme {
-    fn default_style() -> Style<Self> {
-        default
+    fn default_style(&self) -> Appearance {
+        default(self)
     }
 }
 
 impl DefaultStyle for Appearance {
-    fn default_style() -> Style<Self> {
-        |appearance| *appearance
+    fn default_style(&self) -> Appearance {
+        *self
     }
 }
 
diff --git a/widget/src/scrollable.rs b/widget/src/scrollable.rs
index 34312752..c03bbb7d 100644
--- a/widget/src/scrollable.rs
+++ b/widget/src/scrollable.rs
@@ -36,7 +36,7 @@ pub struct Scrollable<
     direction: Direction,
     content: Element<'a, Message, Theme, Renderer>,
     on_scroll: Option<Box<dyn Fn(Viewport) -> Message + 'a>>,
-    style: Style<Theme>,
+    style: Style<'a, Theme>,
 }
 
 impl<'a, Message, Theme, Renderer> Scrollable<'a, Message, Theme, Renderer>
@@ -48,7 +48,7 @@ where
         content: impl Into<Element<'a, Message, Theme, Renderer>>,
     ) -> Self
     where
-        Theme: DefaultStyle,
+        Theme: DefaultStyle + 'a,
     {
         Self::with_direction(content, Direction::default())
     }
@@ -59,20 +59,16 @@ where
         direction: Direction,
     ) -> Self
     where
-        Theme: DefaultStyle,
+        Theme: DefaultStyle + 'a,
     {
-        Self::with_direction_and_style(
-            content,
-            direction,
-            Theme::default_style(),
-        )
+        Self::with_direction_and_style(content, direction, Theme::default_style)
     }
 
     /// Creates a new [`Scrollable`] with the given [`Direction`] and style.
     pub fn with_direction_and_style(
         content: impl Into<Element<'a, Message, Theme, Renderer>>,
         direction: Direction,
-        style: fn(&Theme, Status) -> Appearance,
+        style: impl Fn(&Theme, Status) -> Appearance + 'a,
     ) -> Self {
         let content = content.into();
 
@@ -95,7 +91,7 @@ where
             direction,
             content,
             on_scroll: None,
-            style: style.into(),
+            style: Box::new(style),
         }
     }
 
@@ -126,8 +122,11 @@ where
     }
 
     /// Sets the style of the [`Scrollable`] .
-    pub fn style(mut self, style: fn(&Theme, Status) -> Appearance) -> Self {
-        self.style = style.into();
+    pub fn style(
+        mut self,
+        style: impl Fn(&Theme, Status) -> Appearance + 'a,
+    ) -> Self {
+        self.style = Box::new(style);
         self
     }
 }
@@ -1603,23 +1602,23 @@ pub struct Scroller {
 }
 
 /// The style of a [`Scrollable`].
-pub type Style<Theme> = fn(&Theme, Status) -> Appearance;
+pub type Style<'a, Theme> = Box<dyn Fn(&Theme, Status) -> Appearance + 'a>;
 
 /// The default style of a [`Scrollable`].
 pub trait DefaultStyle {
     /// Returns the default style of a [`Scrollable`].
-    fn default_style() -> Style<Self>;
+    fn default_style(&self, status: Status) -> Appearance;
 }
 
 impl DefaultStyle for Theme {
-    fn default_style() -> Style<Self> {
-        default
+    fn default_style(&self, status: Status) -> Appearance {
+        default(self, status)
     }
 }
 
 impl DefaultStyle for Appearance {
-    fn default_style() -> Style<Self> {
-        |appearance, _status| *appearance
+    fn default_style(&self, _status: Status) -> Appearance {
+        *self
     }
 }
 
diff --git a/widget/src/slider.rs b/widget/src/slider.rs
index f3ea9bfd..d3b46a98 100644
--- a/widget/src/slider.rs
+++ b/widget/src/slider.rs
@@ -49,7 +49,7 @@ pub struct Slider<'a, T, Message, Theme = crate::Theme> {
     on_release: Option<Message>,
     width: Length,
     height: f32,
-    style: Style<Theme>,
+    style: Style<'a, Theme>,
 }
 
 impl<'a, T, Message, Theme> Slider<'a, T, Message, Theme>
@@ -70,7 +70,7 @@ where
     ///   `Message`.
     pub fn new<F>(range: RangeInclusive<T>, value: T, on_change: F) -> Self
     where
-        Theme: DefaultStyle,
+        Theme: DefaultStyle + 'a,
         F: 'a + Fn(T) -> Message,
     {
         let value = if value >= *range.start() {
@@ -95,7 +95,7 @@ where
             on_release: None,
             width: Length::Fill,
             height: Self::DEFAULT_HEIGHT,
-            style: Theme::default_style(),
+            style: Box::new(Theme::default_style),
         }
     }
 
@@ -131,8 +131,11 @@ where
     }
 
     /// Sets the style of the [`Slider`].
-    pub fn style(mut self, style: fn(&Theme, Status) -> Appearance) -> Self {
-        self.style = style.into();
+    pub fn style(
+        mut self,
+        style: impl Fn(&Theme, Status) -> Appearance + 'a,
+    ) -> Self {
+        self.style = Box::new(style);
         self
     }
 
@@ -547,23 +550,23 @@ pub enum HandleShape {
 }
 
 /// The style of a [`Slider`].
-pub type Style<Theme> = fn(&Theme, Status) -> Appearance;
+pub type Style<'a, Theme> = Box<dyn Fn(&Theme, Status) -> Appearance + 'a>;
 
 /// The default style of a [`Slider`].
 pub trait DefaultStyle {
     /// Returns the default style of a [`Slider`].
-    fn default_style() -> Style<Self>;
+    fn default_style(&self, status: Status) -> Appearance;
 }
 
 impl DefaultStyle for Theme {
-    fn default_style() -> Style<Self> {
-        default
+    fn default_style(&self, status: Status) -> Appearance {
+        default(self, status)
     }
 }
 
 impl DefaultStyle for Appearance {
-    fn default_style() -> Style<Self> {
-        |appearance, _status| *appearance
+    fn default_style(&self, _status: Status) -> Appearance {
+        *self
     }
 }
 
diff --git a/widget/src/svg.rs b/widget/src/svg.rs
index 6e61d27a..1ac07ade 100644
--- a/widget/src/svg.rs
+++ b/widget/src/svg.rs
@@ -20,26 +20,26 @@ pub use crate::core::svg::Handle;
 /// [`Svg`] images can have a considerable rendering cost when resized,
 /// specially when they are complex.
 #[allow(missing_debug_implementations)]
-pub struct Svg<Theme = crate::Theme> {
+pub struct Svg<'a, Theme = crate::Theme> {
     handle: Handle,
     width: Length,
     height: Length,
     content_fit: ContentFit,
-    style: Style<Theme>,
+    style: Style<'a, Theme>,
 }
 
-impl<Theme> Svg<Theme> {
+impl<'a, Theme> Svg<'a, Theme> {
     /// Creates a new [`Svg`] from the given [`Handle`].
     pub fn new(handle: impl Into<Handle>) -> Self
     where
-        Theme: DefaultStyle,
+        Theme: DefaultStyle + 'a,
     {
         Svg {
             handle: handle.into(),
             width: Length::Fill,
             height: Length::Shrink,
             content_fit: ContentFit::Contain,
-            style: Theme::default_style(),
+            style: Box::new(Theme::default_style),
         }
     }
 
@@ -48,7 +48,7 @@ impl<Theme> Svg<Theme> {
     #[must_use]
     pub fn from_path(path: impl Into<PathBuf>) -> Self
     where
-        Theme: DefaultStyle,
+        Theme: DefaultStyle + 'a,
     {
         Self::new(Handle::from_path(path))
     }
@@ -80,13 +80,17 @@ impl<Theme> Svg<Theme> {
 
     /// Sets the style variant of this [`Svg`].
     #[must_use]
-    pub fn style(mut self, style: fn(&Theme, Status) -> Appearance) -> Self {
-        self.style = style;
+    pub fn style(
+        mut self,
+        style: impl Fn(&Theme, Status) -> Appearance + 'a,
+    ) -> Self {
+        self.style = Box::new(style);
         self
     }
 }
 
-impl<Message, Theme, Renderer> Widget<Message, Theme, Renderer> for Svg<Theme>
+impl<'a, Message, Theme, Renderer> Widget<Message, Theme, Renderer>
+    for Svg<'a, Theme>
 where
     Renderer: svg::Renderer,
 {
@@ -182,13 +186,13 @@ where
     }
 }
 
-impl<'a, Message, Theme, Renderer> From<Svg<Theme>>
+impl<'a, Message, Theme, Renderer> From<Svg<'a, Theme>>
     for Element<'a, Message, Theme, Renderer>
 where
     Theme: 'a,
     Renderer: svg::Renderer + 'a,
 {
-    fn from(icon: Svg<Theme>) -> Element<'a, Message, Theme, Renderer> {
+    fn from(icon: Svg<'a, Theme>) -> Element<'a, Message, Theme, Renderer> {
         Element::new(icon)
     }
 }
@@ -214,22 +218,22 @@ pub struct Appearance {
 }
 
 /// The style of an [`Svg`].
-pub type Style<Theme> = fn(&Theme, Status) -> Appearance;
+pub type Style<'a, Theme> = Box<dyn Fn(&Theme, Status) -> Appearance + 'a>;
 
 /// The default style of an [`Svg`].
 pub trait DefaultStyle {
     /// Returns the default style of an [`Svg`].
-    fn default_style() -> Style<Self>;
+    fn default_style(&self, status: Status) -> Appearance;
 }
 
 impl DefaultStyle for Theme {
-    fn default_style() -> Style<Self> {
-        |_theme, _status| Appearance::default()
+    fn default_style(&self, _status: Status) -> Appearance {
+        Appearance::default()
     }
 }
 
 impl DefaultStyle for Appearance {
-    fn default_style() -> Style<Self> {
-        |appearance, _status| *appearance
+    fn default_style(&self, _status: Status) -> Appearance {
+        *self
     }
 }
diff --git a/widget/src/text_editor.rs b/widget/src/text_editor.rs
index c7d62d92..5b8f6a1b 100644
--- a/widget/src/text_editor.rs
+++ b/widget/src/text_editor.rs
@@ -41,7 +41,7 @@ pub struct TextEditor<
     width: Length,
     height: Length,
     padding: Padding,
-    style: Style<Theme>,
+    style: Style<'a, Theme>,
     on_edit: Option<Box<dyn Fn(Action) -> Message + 'a>>,
     highlighter_settings: Highlighter::Settings,
     highlighter_format: fn(
@@ -58,7 +58,7 @@ where
     /// Creates new [`TextEditor`] with the given [`Content`].
     pub fn new(content: &'a Content<Renderer>) -> Self
     where
-        Theme: DefaultStyle,
+        Theme: DefaultStyle + 'a,
     {
         Self {
             content,
@@ -68,7 +68,7 @@ where
             width: Length::Fill,
             height: Length::Shrink,
             padding: Padding::new(5.0),
-            style: Theme::default_style(),
+            style: Box::new(Theme::default_style),
             on_edit: None,
             highlighter_settings: (),
             highlighter_format: |_highlight, _theme| {
@@ -142,8 +142,11 @@ where
     }
 
     /// Sets the style of the [`TextEditor`].
-    pub fn style(mut self, style: fn(&Theme, Status) -> Appearance) -> Self {
-        self.style = style.into();
+    pub fn style(
+        mut self,
+        style: impl Fn(&Theme, Status) -> Appearance + 'a,
+    ) -> Self {
+        self.style = Box::new(style);
         self
     }
 }
@@ -809,23 +812,23 @@ pub struct Appearance {
 }
 
 /// The style of a [`TextEditor`].
-pub type Style<Theme> = fn(&Theme, Status) -> Appearance;
+pub type Style<'a, Theme> = Box<dyn Fn(&Theme, Status) -> Appearance + 'a>;
 
 /// The default style of a [`TextEditor`].
 pub trait DefaultStyle {
     /// Returns the default style of a [`TextEditor`].
-    fn default_style() -> Style<Self>;
+    fn default_style(&self, status: Status) -> Appearance;
 }
 
 impl DefaultStyle for Theme {
-    fn default_style() -> Style<Self> {
-        default
+    fn default_style(&self, status: Status) -> Appearance {
+        default(self, status)
     }
 }
 
 impl DefaultStyle for Appearance {
-    fn default_style() -> Style<Self> {
-        |appearance, _status| *appearance
+    fn default_style(&self, _status: Status) -> Appearance {
+        *self
     }
 }
 
diff --git a/widget/src/text_input.rs b/widget/src/text_input.rs
index 9ed8480a..b161ec74 100644
--- a/widget/src/text_input.rs
+++ b/widget/src/text_input.rs
@@ -75,7 +75,7 @@ pub struct TextInput<
     on_paste: Option<Box<dyn Fn(String) -> Message + 'a>>,
     on_submit: Option<Message>,
     icon: Option<Icon<Renderer::Font>>,
-    style: Style<Theme>,
+    style: Style<'a, Theme>,
 }
 
 /// The default [`Padding`] of a [`TextInput`].
@@ -90,9 +90,9 @@ where
     /// its current value.
     pub fn new(placeholder: &str, value: &str) -> Self
     where
-        Theme: DefaultStyle,
+        Theme: DefaultStyle + 'a,
     {
-        Self::with_style(placeholder, value, Theme::default_style())
+        Self::with_style(placeholder, value, Theme::default_style)
     }
 
     /// Creates a new [`TextInput`] with the given placeholder,
@@ -100,7 +100,7 @@ where
     pub fn with_style(
         placeholder: &str,
         value: &str,
-        style: fn(&Theme, Status) -> Appearance,
+        style: impl Fn(&Theme, Status) -> Appearance + 'a,
     ) -> Self {
         TextInput {
             id: None,
@@ -116,7 +116,7 @@ where
             on_paste: None,
             on_submit: None,
             icon: None,
-            style: style.into(),
+            style: Box::new(style),
         }
     }
 
@@ -203,8 +203,11 @@ where
     }
 
     /// Sets the style of the [`TextInput`].
-    pub fn style(mut self, style: fn(&Theme, Status) -> Appearance) -> Self {
-        self.style = style.into();
+    pub fn style(
+        mut self,
+        style: impl Fn(&Theme, Status) -> Appearance + 'a,
+    ) -> Self {
+        self.style = Box::new(style);
         self
     }
 
@@ -1413,23 +1416,23 @@ pub struct Appearance {
 }
 
 /// The style of a [`TextInput`].
-pub type Style<Theme> = fn(&Theme, Status) -> Appearance;
+pub type Style<'a, Theme> = Box<dyn Fn(&Theme, Status) -> Appearance + 'a>;
 
 /// The default style of a [`TextInput`].
 pub trait DefaultStyle {
     /// Returns the default style of a [`TextInput`].
-    fn default_style() -> Style<Self>;
+    fn default_style(&self, status: Status) -> Appearance;
 }
 
 impl DefaultStyle for Theme {
-    fn default_style() -> Style<Self> {
-        default
+    fn default_style(&self, status: Status) -> Appearance {
+        default(self, status)
     }
 }
 
 impl DefaultStyle for Appearance {
-    fn default_style() -> Style<Self> {
-        |appearance, _status| *appearance
+    fn default_style(&self, _status: Status) -> Appearance {
+        *self
     }
 }
 
diff --git a/widget/src/toggler.rs b/widget/src/toggler.rs
index 9e81ba33..fc9e06e1 100644
--- a/widget/src/toggler.rs
+++ b/widget/src/toggler.rs
@@ -48,7 +48,7 @@ pub struct Toggler<
     text_shaping: text::Shaping,
     spacing: f32,
     font: Option<Renderer::Font>,
-    style: Style<Theme>,
+    style: Style<'a, Theme>,
 }
 
 impl<'a, Message, Theme, Renderer> Toggler<'a, Message, Theme, Renderer>
@@ -72,7 +72,7 @@ where
         f: F,
     ) -> Self
     where
-        Theme: DefaultStyle,
+        Theme: 'a + DefaultStyle,
         F: 'a + Fn(bool) -> Message,
     {
         Toggler {
@@ -87,7 +87,7 @@ where
             text_shaping: text::Shaping::Basic,
             spacing: Self::DEFAULT_SIZE / 2.0,
             font: None,
-            style: Theme::default_style(),
+            style: Box::new(Theme::default_style),
         }
     }
 
@@ -145,8 +145,11 @@ where
     }
 
     /// Sets the style of the [`Toggler`].
-    pub fn style(mut self, style: fn(&Theme, Status) -> Appearance) -> Self {
-        self.style = style.into();
+    pub fn style(
+        mut self,
+        style: impl Fn(&Theme, Status) -> Appearance + 'a,
+    ) -> Self {
+        self.style = Box::new(style);
         self
     }
 }
@@ -398,23 +401,23 @@ pub struct Appearance {
 }
 
 /// The style of a [`Toggler`].
-pub type Style<Theme> = fn(&Theme, Status) -> Appearance;
+pub type Style<'a, Theme> = Box<dyn Fn(&Theme, Status) -> Appearance + 'a>;
 
 /// The default style of a [`Toggler`].
 pub trait DefaultStyle {
     /// Returns the default style of a [`Toggler`].
-    fn default_style() -> Style<Self>;
+    fn default_style(&self, status: Status) -> Appearance;
 }
 
 impl DefaultStyle for Theme {
-    fn default_style() -> Style<Self> {
-        default
+    fn default_style(&self, status: Status) -> Appearance {
+        default(self, status)
     }
 }
 
 impl DefaultStyle for Appearance {
-    fn default_style() -> Style<Self> {
-        |appearance, _status| *appearance
+    fn default_style(&self, _status: Status) -> Appearance {
+        *self
     }
 }
 
diff --git a/widget/src/tooltip.rs b/widget/src/tooltip.rs
index 8c8ee983..8e11ca98 100644
--- a/widget/src/tooltip.rs
+++ b/widget/src/tooltip.rs
@@ -28,7 +28,7 @@ pub struct Tooltip<
     gap: f32,
     padding: f32,
     snap_within_viewport: bool,
-    style: container::Style<Theme>,
+    style: container::Style<'a, Theme>,
 }
 
 impl<'a, Message, Theme, Renderer> Tooltip<'a, Message, Theme, Renderer>
@@ -47,7 +47,7 @@ where
         position: Position,
     ) -> Self
     where
-        Theme: container::DefaultStyle,
+        Theme: container::DefaultStyle + 'a,
     {
         Tooltip {
             content: content.into(),
@@ -56,7 +56,7 @@ where
             gap: 0.0,
             padding: Self::DEFAULT_PADDING,
             snap_within_viewport: true,
-            style: Theme::default_style(),
+            style: Box::new(Theme::default_style),
         }
     }
 
@@ -81,9 +81,9 @@ where
     /// Sets the style of the [`Tooltip`].
     pub fn style(
         mut self,
-        style: fn(&Theme, container::Status) -> container::Appearance,
+        style: impl Fn(&Theme, container::Status) -> container::Appearance + 'a,
     ) -> Self {
-        self.style = style.into();
+        self.style = Box::new(style);
         self
     }
 }
@@ -239,7 +239,7 @@ where
                 positioning: self.position,
                 gap: self.gap,
                 padding: self.padding,
-                style: self.style,
+                style: &self.style,
             })))
         } else {
             None
@@ -309,7 +309,8 @@ where
     positioning: Position,
     gap: f32,
     padding: f32,
-    style: container::Style<Theme>,
+    style:
+        &'b (dyn Fn(&Theme, container::Status) -> container::Appearance + 'a),
 }
 
 impl<'a, 'b, Message, Theme, Renderer>
diff --git a/widget/src/vertical_slider.rs b/widget/src/vertical_slider.rs
index f7030584..2aa8f4d1 100644
--- a/widget/src/vertical_slider.rs
+++ b/widget/src/vertical_slider.rs
@@ -51,7 +51,7 @@ pub struct VerticalSlider<'a, T, Message, Theme = crate::Theme> {
     on_release: Option<Message>,
     width: f32,
     height: Length,
-    style: Style<Theme>,
+    style: Style<'a, Theme>,
 }
 
 impl<'a, T, Message, Theme> VerticalSlider<'a, T, Message, Theme>
@@ -72,7 +72,7 @@ where
     ///   `Message`.
     pub fn new<F>(range: RangeInclusive<T>, value: T, on_change: F) -> Self
     where
-        Theme: DefaultStyle,
+        Theme: DefaultStyle + 'a,
         F: 'a + Fn(T) -> Message,
     {
         let value = if value >= *range.start() {
@@ -97,7 +97,7 @@ where
             on_release: None,
             width: Self::DEFAULT_WIDTH,
             height: Length::Fill,
-            style: Theme::default_style(),
+            style: Box::new(Theme::default_style),
         }
     }
 
@@ -133,8 +133,11 @@ where
     }
 
     /// Sets the style of the [`VerticalSlider`].
-    pub fn style(mut self, style: fn(&Theme, Status) -> Appearance) -> Self {
-        self.style = style.into();
+    pub fn style(
+        mut self,
+        style: impl Fn(&Theme, Status) -> Appearance + 'a,
+    ) -> Self {
+        self.style = Box::new(style);
         self
     }