Merge remote-tracking branch 'origin/master' into feat/multi-window-support

# Conflicts:
#	Cargo.toml
#	core/src/window/icon.rs
#	core/src/window/id.rs
#	core/src/window/position.rs
#	core/src/window/settings.rs
#	examples/integration/src/main.rs
#	examples/integration_opengl/src/main.rs
#	glutin/src/application.rs
#	native/src/subscription.rs
#	native/src/window.rs
#	runtime/src/window/action.rs
#	src/lib.rs
#	src/window.rs
#	winit/Cargo.toml
#	winit/src/application.rs
#	winit/src/icon.rs
#	winit/src/settings.rs
#	winit/src/window.rs

runtime/src/command/action.rs

@@ -0,0 +1,88 @@
+use crate::clipboard;
+use crate::core::widget;
+use crate::font;
+use crate::system;
+use crate::window;
+
+use iced_futures::MaybeSend;
+
+use std::borrow::Cow;
+use std::fmt;
+
+/// An action that a [`Command`] can perform.
+///
+/// [`Command`]: crate::Command
+pub enum Action<T> {
+    /// Run a [`Future`] to completion.
+    ///
+    /// [`Future`]: iced_futures::BoxFuture
+    Future(iced_futures::BoxFuture<T>),
+
+    /// Run a clipboard action.
+    Clipboard(clipboard::Action<T>),
+
+    /// Run a window action.
+    Window(window::Id, window::Action<T>),
+
+    /// Run a system action.
+    System(system::Action<T>),
+
+    /// Run a widget action.
+    Widget(Box<dyn widget::Operation<T>>),
+
+    /// Load a font from its bytes.
+    LoadFont {
+        /// The bytes of the font to load.
+        bytes: Cow<'static, [u8]>,
+
+        /// The message to produce when the font has been loaded.
+        tagger: Box<dyn Fn(Result<(), font::Error>) -> T>,
+    },
+}
+
+impl<T> Action<T> {
+    /// Applies a transformation to the result of a [`Command`].
+    ///
+    /// [`Command`]: crate::Command
+    pub fn map<A>(
+        self,
+        f: impl Fn(T) -> A + 'static + MaybeSend + Sync,
+    ) -> Action<A>
+    where
+        A: 'static,
+        T: 'static,
+    {
+        use iced_futures::futures::FutureExt;
+
+        match self {
+            Self::Future(future) => Action::Future(Box::pin(future.map(f))),
+            Self::Clipboard(action) => Action::Clipboard(action.map(f)),
+            Self::Window(id, window) => Action::Window(id, window.map(f)),
+            Self::System(system) => Action::System(system.map(f)),
+            Self::Widget(operation) => {
+                Action::Widget(Box::new(widget::operation::map(operation, f)))
+            }
+            Self::LoadFont { bytes, tagger } => Action::LoadFont {
+                bytes,
+                tagger: Box::new(move |result| f(tagger(result))),
+            },
+        }
+    }
+}
+
+impl<T> fmt::Debug for Action<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Future(_) => write!(f, "Action::Future"),
+            Self::Clipboard(action) => {
+                write!(f, "Action::Clipboard({action:?})")
+            }
+            Self::Window(id, action) => {
+                write!(f, "Action::Window({id:?}, {action:?})")
+            }
+            Self::System(action) => write!(f, "Action::System({action:?})"),
+            Self::Widget(_action) => write!(f, "Action::Widget"),
+            Self::LoadFont { .. } => write!(f, "Action::LoadFont"),
+        }
+    }
+}