Switcher unmounts in all windows

Fixes #139

CHANGELOG.md

@@ -17,6 +17,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   animating the transition. The previous behavior caused nested collapsed
   widgets to grow and shrink in an accordian-like fashion rather than animating
   together.
+- `Switcher` now unmounts child widgets in all windows it is mounted in. Fixes
+  [#139][139].
 
 ### Added
 
@@ -35,6 +37,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   - `MakeWidget::to_checkbox()`
   - `WidgetInstance::to_window()`
 
+[139]: https://github.com/khonsulabs/cushy/issues/139
+
 ## v0.4.0 (2024-08-20)
 
 ### Breaking Changes

Cargo.lock

@@ -123,9 +123,9 @@ checksum = "b3d1d046238990b9cf5bcde22a3fb3584ee5cf65fb2765f454ed428c7a0063da"
 
 [[package]]
 name = "appit"
-version = "0.3.1"
+version = "0.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e6869c02a8fdc42d78e60388824dbd5e331f763a7e1b8530eff4ea5c56df3438"
+checksum = "7a158c9d2660ce603c741d513b44cdd97a4553e0749d4e49e45b9480fc72c162"
 dependencies = [
  "winit",
 ]
@@ -171,7 +171,7 @@ checksum = "0ae92a5119aa49cdbcf6b9f893fe4e1d98b04ccbf82ee0584ad948a44a734dea"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.75",
+ "syn 2.0.76",
 ]
 
 [[package]]
@@ -209,32 +209,32 @@ checksum = "1505bd5d3d116872e7271a6d4e16d81d0c8570876c8de68093a09ac269d8aac0"
 
 [[package]]
 name = "attribute-derive"
-version = "0.10.0"
+version = "0.10.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9f6763469f78790650fe2b25ea8c2947b1bf5889b7be7833e23f383437fa8fc5"
+checksum = "36f18fc482cf559bca9efe778ba2fd0d1c16a31d5d24a2c886ed16b2d217e454"
 dependencies = [
  "attribute-derive-macro",
  "derive-where",
  "manyhow",
  "proc-macro2",
  "quote",
- "syn 2.0.75",
+ "syn 2.0.76",
 ]
 
 [[package]]
 name = "attribute-derive-macro"
-version = "0.10.0"
+version = "0.10.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c1318b422e4ad618775982a521842870d74ab4e07cf7588a968bc6d68c62a4ff"
+checksum = "a85958950e587256a16c72325ff3c4f3e4db25999173e9ca2864665be84ff63b"
 dependencies = [
  "collection_literals",
  "interpolator",
  "manyhow",
- "proc-macro-utils 0.10.0",
+ "proc-macro-utils",
  "proc-macro2",
  "quote",
  "quote-use",
- "syn 2.0.75",
+ "syn 2.0.76",
 ]
 
 [[package]]
@@ -316,9 +316,9 @@ checksum = "b048fb63fd8b5923fc5aa7b340d8e156aec7ec02f0c78fa8a6ddc2613f6f71de"
 
 [[package]]
 name = "bitstream-io"
-version = "2.5.1"
+version = "2.5.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "586ebf43072a4f103bc979b12dc36bc82bed5c2a340e16344e1253d53263c3fa"
+checksum = "b81e1519b0d82120d2fd469d5bfb2919a9361c48b02d82d04befc1cdd2002452"
 
 [[package]]
 name = "block"
@@ -355,9 +355,9 @@ checksum = "64fa3c856b712db6612c019f14756e64e4bcea13337a6b33b696333a9eaa2d06"
 
 [[package]]
 name = "bytemuck"
-version = "1.17.0"
+version = "1.17.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6fd4c6dcc3b0aea2f5c0b4b82c2b15fe39ddbc76041a310848f4706edf76bb31"
+checksum = "773d90827bc3feecfb67fab12e24de0749aad83c74b9504ecde46237b5cd24e2"
 dependencies = [
  "bytemuck_derive",
 ]
@@ -370,7 +370,7 @@ checksum = "0cc8b54b395f2fcfbb3d90c47b01c7f444d94d05bdeb775811dec868ac3bbc26"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.75",
+ "syn 2.0.76",
 ]
 
 [[package]]
@@ -419,9 +419,9 @@ dependencies = [
 
 [[package]]
 name = "cc"
-version = "1.1.13"
+version = "1.1.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "72db2f7947ecee9b03b510377e8bb9077afa27176fdbff55c51027e976fdcc48"
+checksum = "57b6a275aa2903740dc87da01c62040406b8812552e97129a63ea8850a17c6e6"
 dependencies = [
  "jobserver",
  "libc",
@@ -704,7 +704,7 @@ dependencies = [
  "proc-macro2",
  "quote",
  "quote-use",
- "syn 2.0.75",
+ "syn 2.0.76",
 ]
 
 [[package]]
@@ -726,7 +726,7 @@ checksum = "62d671cc41a825ebabc75757b62d3d168c577f9149b2d49ece1dad1f72119d25"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.75",
+ "syn 2.0.76",
 ]
 
 [[package]]
@@ -817,9 +817,9 @@ dependencies = [
 
 [[package]]
 name = "euclid"
-version = "0.22.10"
+version = "0.22.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e0f0eb73b934648cd7a4a61f1b15391cd95dab0b4da6e2e66c2a072c144b4a20"
+checksum = "ad9cdb4b747e485a12abb0e6566612956c7a1bafa3bdb8d682c5b6d403589e48"
 dependencies = [
  "num-traits",
 ]
@@ -870,9 +870,9 @@ dependencies = [
 
 [[package]]
 name = "flate2"
-version = "1.0.32"
+version = "1.0.33"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9c0596c1eac1f9e04ed902702e9878208b336edc9d6fddc8a48387349bab3666"
+checksum = "324a1be68054ef05ad64b861cc9eaf1d623d2d8cb25b4bf2cb9cdd902b4bf253"
 dependencies = [
  "crc32fast",
  "miniz_oxide 0.8.0",
@@ -943,7 +943,7 @@ checksum = "1a5c6c585bc94aaf2c7b51dd4c2ba22680844aba4c687be581871a6f518c5742"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.75",
+ "syn 2.0.76",
 ]
 
 [[package]]
@@ -1214,7 +1214,7 @@ checksum = "c34819042dc3d3971c46c2190835914dfbe0c3c13f61449b2997f4e9722dfa60"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.75",
+ "syn 2.0.76",
 ]
 
 [[package]]
@@ -1476,23 +1476,23 @@ dependencies = [
 
 [[package]]
 name = "manyhow"
-version = "0.11.3"
+version = "0.11.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a5b8ea82a2287fe7b26aea89c0c02957886d7e97eabffc1f9d2031feaa6f82e6"
+checksum = "b33efb3ca6d3b07393750d4030418d594ab1139cee518f0dc88db70fec873587"
 dependencies = [
  "manyhow-macros",
  "proc-macro2",
  "quote",
- "syn 2.0.75",
+ "syn 2.0.76",
 ]
 
 [[package]]
 name = "manyhow-macros"
-version = "0.11.3"
+version = "0.11.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ae36e8d9b4095531e43de72ed424f0f4a98cba40f7e5a99366f9818769489272"
+checksum = "46fce34d199b78b6e6073abf984c9cf5fd3e9330145a93ee0738a7443e371495"
 dependencies = [
- "proc-macro-utils 0.8.0",
+ "proc-macro-utils",
  "proc-macro2",
  "quote",
 ]
@@ -1686,7 +1686,7 @@ checksum = "ed3955f1a9c7c0c15e092f9c887db08b1fc683305fdf6eb6684f22555355e202"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.75",
+ "syn 2.0.76",
 ]
 
 [[package]]
@@ -1737,7 +1737,7 @@ dependencies = [
  "proc-macro-crate",
  "proc-macro2",
  "quote",
- "syn 2.0.75",
+ "syn 2.0.76",
 ]
 
 [[package]]
@@ -2012,7 +2012,7 @@ dependencies = [
  "by_address",
  "proc-macro2",
  "quote",
- "syn 2.0.75",
+ "syn 2.0.76",
 ]
 
 [[package]]
@@ -2080,7 +2080,7 @@ dependencies = [
  "phf_shared",
  "proc-macro2",
  "quote",
- "syn 2.0.75",
+ "syn 2.0.76",
 ]
 
 [[package]]
@@ -2109,7 +2109,7 @@ checksum = "2f38a4412a78282e09a2cf38d195ea5420d15ba0602cb375210efbc877243965"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.75",
+ "syn 2.0.76",
 ]
 
 [[package]]
@@ -2193,32 +2193,21 @@ checksum = "e8cf8e6a8aa66ce33f63993ffc4ea4271eb5b0530a9002db8455ea6050c77bfa"
 
 [[package]]
 name = "prettyplease"
-version = "0.2.20"
+version = "0.2.22"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5f12335488a2f3b0a83b14edad48dca9879ce89b2edd10e80237e4e852dd645e"
+checksum = "479cf940fbbb3426c32c5d5176f62ad57549a0bb84773423ba8be9d089f5faba"
 dependencies = [
  "proc-macro2",
- "syn 2.0.75",
+ "syn 2.0.76",
 ]
 
 [[package]]
 name = "proc-macro-crate"
-version = "3.1.0"
+version = "3.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6d37c51ca738a55da99dc0c4a34860fd675453b8b36209178c2249bb13651284"
+checksum = "8ecf48c7ca261d60b74ab1a7b20da18bede46776b2e55535cb958eb595c5fa7b"
 dependencies = [
- "toml_edit 0.21.1",
+ "toml_edit",
-]
-
-[[package]]
-name = "proc-macro-utils"
-version = "0.8.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3f59e109e2f795a5070e69578c4dc101068139f74616778025ae1011d4cd41a8"
-dependencies = [
- "proc-macro2",
- "quote",
- "smallvec",
 ]
 
 [[package]]
@@ -2257,7 +2246,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8021cf59c8ec9c432cfc2526ac6b8aa508ecaf29cd415f271b8406c1b851c3fd"
 dependencies = [
  "quote",
- "syn 2.0.75",
+ "syn 2.0.76",
 ]
 
 [[package]]
@@ -2286,18 +2275,18 @@ dependencies = [
 
 [[package]]
 name = "quote"
-version = "1.0.36"
+version = "1.0.37"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0fa76aaf39101c457836aec0ce2316dbdc3ab723cdda1c6bd4e6ad4208acaca7"
+checksum = "b5b9d34b8991d19d98081b46eacdd8eb58c6f2b201139f7c5f643cc155a633af"
 dependencies = [
  "proc-macro2",
 ]
 
 [[package]]
 name = "quote-use"
-version = "0.8.3"
+version = "0.8.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "48e96ac59974192a2fa6ee55a41211cf1385c5b2a8636a4c3068b3b3dd599ece"
+checksum = "9619db1197b497a36178cfc736dc96b271fe918875fbf1344c436a7e93d0321e"
 dependencies = [
  "quote",
  "quote-use-macros",
@@ -2305,15 +2294,14 @@ dependencies = [
 
 [[package]]
 name = "quote-use-macros"
-version = "0.8.3"
+version = "0.8.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b4c57308e9dde4d7be9af804f6deeaa9951e1de1d5ffce6142eb964750109f7e"
+checksum = "82ebfb7faafadc06a7ab141a6f67bcfb24cb8beb158c6fe933f2f035afa99f35"
 dependencies = [
- "derive-where",
+ "proc-macro-utils",
- "proc-macro-utils 0.8.0",
  "proc-macro2",
  "quote",
- "syn 2.0.75",
+ "syn 2.0.76",
 ]
 
 [[package]]
@@ -2540,9 +2528,9 @@ checksum = "08d43f7aa6b08d49f382cde6a7982047c3426db949b1424bc4b7ec9ae12c6ce2"
 
 [[package]]
 name = "rustix"
-version = "0.38.34"
+version = "0.38.35"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "70dc5ec042f7a43c4a73241207cecc9873a06d45debb38b329f8541d85c2730f"
+checksum = "a85d50532239da68e9addb745ba38ff4612a242c1c7ceea689c4bc7c2f43c36f"
 dependencies = [
  "bitflags 2.6.0",
  "errno",
@@ -2610,22 +2598,22 @@ checksum = "d369a96f978623eb3dc28807c4852d6cc617fed53da5d3c400feff1ef34a714a"
 
 [[package]]
 name = "serde"
-version = "1.0.208"
+version = "1.0.209"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cff085d2cb684faa248efb494c39b68e522822ac0de72ccf08109abde717cfb2"
+checksum = "99fce0ffe7310761ca6bf9faf5115afbc19688edd00171d81b1bb1b116c63e09"
 dependencies = [
  "serde_derive",
 ]
 
 [[package]]
 name = "serde_derive"
-version = "1.0.208"
+version = "1.0.209"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "24008e81ff7613ed8e5ba0cfaf24e2c2f1e5b8a0495711e44fcd4882fca62bcf"
+checksum = "a5831b979fd7b5439637af1752d535ff49f4860c0f341d1baeb6faf0f4242170"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.75",
+ "syn 2.0.76",
 ]
 
 [[package]]
@@ -2807,9 +2795,9 @@ dependencies = [
 
 [[package]]
 name = "syn"
-version = "2.0.75"
+version = "2.0.76"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f6af063034fc1935ede7be0122941bafa9bacb949334d090b77ca98b5817c7d9"
+checksum = "578e081a14e0cefc3279b0472138c513f37b41a08d5a3cca9b6e4e8ceb6cd525"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -2870,7 +2858,7 @@ checksum = "a4558b58466b9ad7ca0f102865eccc95938dca1a74a856f2b57b6629050da261"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.75",
+ "syn 2.0.76",
 ]
 
 [[package]]
@@ -2953,7 +2941,7 @@ dependencies = [
  "serde",
  "serde_spanned",
  "toml_datetime",
- "toml_edit 0.22.20",
+ "toml_edit",
 ]
 
 [[package]]
@@ -2965,17 +2953,6 @@ dependencies = [
  "serde",
 ]
 
-[[package]]
-name = "toml_edit"
-version = "0.21.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6a8534fd7f78b5405e860340ad6575217ce99f38d4d5c8f2442cb5ecb50090e1"
-dependencies = [
- "indexmap",
- "toml_datetime",
- "winnow 0.5.40",
-]
-
 [[package]]
 name = "toml_edit"
 version = "0.22.20"
@@ -2986,7 +2963,7 @@ dependencies = [
  "serde",
  "serde_spanned",
  "toml_datetime",
- "winnow 0.6.18",
+ "winnow",
 ]
 
 [[package]]
@@ -3008,7 +2985,7 @@ checksum = "34704c8d6ebcbc939824180af020566b01a7c01f80641264eba0999f6c2b6be7"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.75",
+ "syn 2.0.76",
 ]
 
 [[package]]
@@ -3195,7 +3172,7 @@ dependencies = [
  "once_cell",
  "proc-macro2",
  "quote",
- "syn 2.0.75",
+ "syn 2.0.76",
  "wasm-bindgen-shared",
 ]
 
@@ -3229,7 +3206,7 @@ checksum = "afc340c74d9005395cf9dd098506f7f44e38f2b4a21c6aaacf9a105ea5e1e836"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.75",
+ "syn 2.0.76",
  "wasm-bindgen-backend",
  "wasm-bindgen-shared",
 ]
@@ -3803,15 +3780,6 @@ dependencies = [
  "xkbcommon-dl",
 ]
 
-[[package]]
-name = "winnow"
-version = "0.5.40"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f593a95398737aeed53e489c785df13f3618e41dbcd6718c6addbf1395aa6876"
-dependencies = [
- "memchr",
-]
-
 [[package]]
 name = "winnow"
 version = "0.6.18"
@@ -3914,7 +3882,7 @@ checksum = "fa4f8080344d4671fb4e831a13ad1e68092748387dfc4f55e356242fae12ce3e"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.75",
+ "syn 2.0.76",
 ]
 
 [[package]]

examples/shared-switcher.rs

@@ -0,0 +1,53 @@
+//! Shows the ability to share widgets between multiple windows.
+//!
+//! This example was created to test a fix for
+//! <https://github.com/khonsulabs/cushy/issues/139>. The issue was that if the
+//! same Switcher widget was shown on two separate windows, only one window
+//! would unmount the existing widget.
+//!
+//! When running this example after the bug has been fixed, unmounted messages
+//! should be printed twice: once per each window.
+use cushy::value::{Dynamic, Switchable};
+use cushy::widget::MakeWidget;
+use cushy::widgets::Custom;
+use cushy::{Open, PendingApp, Run};
+
+#[derive(Debug, Clone, Copy, Eq, PartialEq)]
+enum Contents {
+    A,
+    B,
+}
+
+fn main() -> cushy::Result {
+    let mut app = PendingApp::default();
+
+    let selected = Dynamic::new(Contents::A);
+
+    // Open up another window containing our controls
+    selected
+        .new_radio(Contents::A, "A")
+        .and(selected.new_radio(Contents::B, "B"))
+        .into_rows()
+        .open(&mut app)?;
+
+    let display = selected
+        .switcher(|contents, _| match contents {
+            Contents::A => Custom::new("A")
+                .on_unmounted(|_| {
+                    println!("A unmounted");
+                })
+                .make_widget(),
+            Contents::B => Custom::new("B")
+                .on_unmounted(|_| {
+                    println!("B unmounted");
+                })
+                .make_widget(),
+        })
+        .make_widget();
+
+    // Open two windows with the same switcher instance
+    display.to_window().open(&mut app)?;
+    display.to_window().open(&mut app)?;
+
+    app.run()
+}

src/widget.rs

@@ -2499,6 +2499,12 @@ impl WidgetRef {
     }
 }
 
+impl From<WidgetRef> for WindowLocal<MountedWidget> {
+    fn from(value: WidgetRef) -> Self {
+        value.mounted
+    }
+}
+
 impl AsRef<WidgetId> for WidgetRef {
     fn as_ref(&self) -> &WidgetId {
         self.instance.as_ref()

src/widgets/switcher.rs

@@ -1,10 +1,14 @@
 use std::fmt::Debug;
+use std::mem;
 
+use ahash::HashMap;
 use figures::Size;
+use kludgine::KludgineId;
 
-use crate::context::LayoutContext;
+use crate::context::{AsEventContext, LayoutContext};
 use crate::value::{Dynamic, DynamicReader, IntoDynamic, IntoReader, Source};
-use crate::widget::{WidgetInstance, WidgetRef, WrapperWidget};
+use crate::widget::{MountedWidget, WidgetInstance, WidgetRef, WrapperWidget};
+use crate::window::WindowLocal;
 use crate::ConstraintLimit;
 
 /// A widget that switches its contents based on a value of `T`.
@@ -12,6 +16,7 @@ use crate::ConstraintLimit;
 pub struct Switcher {
     source: DynamicReader<WidgetInstance>,
     child: WidgetRef,
+    pending_unmount: HashMap<KludgineId, MountedWidget>,
 }
 
 impl Switcher {
@@ -39,7 +44,11 @@ impl Switcher {
     pub fn new(source: impl IntoReader<WidgetInstance>) -> Self {
         let source = source.into_reader();
         let child = WidgetRef::new(source.get());
-        Self { source, child }
+        Self {
+            source,
+            child,
+            pending_unmount: HashMap::default(),
+        }
     }
 }
 
@@ -54,12 +63,32 @@ impl WrapperWidget for Switcher {
         available_space: Size<ConstraintLimit>,
         context: &mut LayoutContext<'_, '_, '_, '_>,
     ) -> Size<ConstraintLimit> {
+        if let Some(pending_unmount) = self.pending_unmount.remove(&context.kludgine_id()) {
+            context.remove_child(&pending_unmount);
+        }
+
         let current_source = self.source.get_tracking_invalidate(context);
         if &current_source != self.child.widget() {
+            // immediately unmount in the current context.
             self.child.unmount_in(context);
-            self.child = WidgetRef::new(current_source);
+            let old_mounts = <WindowLocal<MountedWidget>>::from(mem::replace(
+                &mut self.child,
+                WidgetRef::new(current_source),
+            ));
+
+            // For all other contexts, we have to wait until this callback to
+            // try unmounting.
+            for (id, mounted) in old_mounts {
+                let existing = self.pending_unmount.insert(id, mounted);
+                debug_assert!(
+                    existing.is_none(),
+                    "Existing unmount found, but should have already been unmounted"
+                );
+            }
         }
+
         context.invalidate_when_changed(&self.source);
+
         available_space
     }
 }

src/window.rs

@@ -2439,10 +2439,26 @@ impl<T> WindowLocal<T> {
         self.by_window.get(&context.kludgine_id())
     }
 
+    /// Looks up an exclusive reference to the value for this window, returning
+    /// None if not found.
+    ///
+    /// Internally this API uses [`HashMap::get`](hash_map::HashMap::get).
+    #[must_use]
+    pub fn get_mut(&mut self, context: &WidgetContext<'_>) -> Option<&mut T> {
+        self.by_window.get_mut(&context.kludgine_id())
+    }
+
     /// Removes any stored value for this window.
     pub fn clear_for(&mut self, context: &WidgetContext<'_>) -> Option<T> {
         self.by_window.remove(&context.kludgine_id())
     }
+
+    /// Returns an iterator over the per-window values stored in this
+    /// collection.
+    #[must_use]
+    pub fn iter(&self) -> hash_map::Iter<'_, KludgineId, T> {
+        self.into_iter()
+    }
 }
 
 impl<T> Default for WindowLocal<T> {
@@ -2453,6 +2469,24 @@ impl<T> Default for WindowLocal<T> {
     }
 }
 
+impl<T> IntoIterator for WindowLocal<T> {
+    type IntoIter = hash_map::IntoIter<KludgineId, T>;
+    type Item = (KludgineId, T);
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.by_window.into_iter()
+    }
+}
+
+impl<'a, T> IntoIterator for &'a WindowLocal<T> {
+    type IntoIter = hash_map::Iter<'a, KludgineId, T>;
+    type Item = (&'a KludgineId, &'a T);
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.by_window.iter()
+    }
+}
+
 /// The state of a [`VirtualWindow`].
 pub struct VirtualState {
     /// State that may be updated outside of the window's event callbacks.